GH-33143: [C++] Kernel to convert timestamp with timezone to wall time#34208

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Merged
westonpace merged 4 commits into from
Feb 17, 2023
Merged

GH-33143: [C++] Kernel to convert timestamp with timezone to wall time #34208

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8857c38
Adding local_time kernel
rok Feb 15, 2023
a5185a2
More test cases. Python tests.
rok Feb 16, 2023
115347e
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1 change: 1 addition & 0 deletions cpp/src/arrow/compute/api_scalar.cc
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Original file line numberDiff line numberDiff line change
Expand Up@@ -834,6 +834,7 @@ SCALAR_EAGER_UNARY(DayOfYear, "day_of_year")
SCALAR_EAGER_UNARY(Hour, "hour")
SCALAR_EAGER_UNARY(YearMonthDay, "year_month_day")
SCALAR_EAGER_UNARY(IsDaylightSavings, "is_dst")
SCALAR_EAGER_UNARY(LocalTime, "local_time")
SCALAR_EAGER_UNARY(IsLeapYear, "is_leap_year")
SCALAR_EAGER_UNARY(ISOCalendar, "iso_calendar")
SCALAR_EAGER_UNARY(ISOWeek, "iso_week")
Expand Down
10 changes: 10 additions & 0 deletions cpp/src/arrow/compute/api_scalar.h
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Original file line numberDiff line numberDiff line change
Expand Up@@ -1518,6 +1518,16 @@ ARROW_EXPORT Result<Datum> AssumeTimezone(const Datum& values,
ARROW_EXPORT Result<Datum> IsDaylightSavings(const Datum& values,
ExecContext* ctx = NULLPTR);

/// \brief LocalTime converts timestamp to timezone naive local timestamp
///
/// \param[in] values input to convert to local time
/// \param[in] ctx the function execution context, optional
/// \return the resulting datum
///
/// \since 12.0.0
/// \note API not yet finalized

@westonpacewestonpaceFeb 17, 2023

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I was going to suggest removing this but now I see this is everywhere. Hmm.... :( I'm not sure how true this is these days.

@rokrokFeb 17, 2023

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Well, you could see it as an opportunity to sync the API with substrait :D

ARROW_EXPORT Result<Datum> LocalTime(const Datum& values, ExecContext* ctx = NULLPTR);

/// \brief Years Between finds the number of years between two values
///
/// \param[in] left input treated as the start time
Expand Down
33 changes: 33 additions & 0 deletions cpp/src/arrow/compute/kernels/scalar_temporal_test.cc
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Original file line numberDiff line numberDiff line change
Expand Up@@ -1811,6 +1811,39 @@ TEST_F(ScalarTemporalTest, TestTemporalDifferenceErrors) {
CallFunction("weeks_between", {arr1, arr1}, &options));
}

TEST_F(ScalarTemporalTest, TestLocalTime) {
const char* times_seconds_precision =
R"(["1970-01-01T00:00:59", "2000-02-29T23:23:23", "2033-05-18T03:33:20",
"2020-01-01T01:05:05", "2019-12-31T02:10:10", "2019-12-30T03:15:15",
"2009-12-31T04:20:20", "2010-01-01T05:25:25", "2010-01-03T06:30:30",
"2010-01-04T07:35:35", "2006-01-01T08:40:40", "2005-12-31T09:45:45",
"2008-12-28", "2008-12-29", "2012-01-01 01:02:03", null])";

const char* expected_local_kolkata =
R"(["1970-01-01 05:30:59", "2000-03-01 04:53:23", "2033-05-18 09:03:20",
"2020-01-01 06:35:05", "2019-12-31 07:40:10", "2019-12-30 08:45:15",
"2009-12-31 09:50:20", "2010-01-01 10:55:25", "2010-01-03 12:00:30",
"2010-01-04 13:05:35", "2006-01-01 14:10:40", "2005-12-31 15:15:45",
"2008-12-28 05:30:00", "2008-12-29 05:30:00", "2012-01-01 06:32:03", null])";
const char* expected_local_marquesas =
R"(["1969-12-31 14:30:59", "2000-02-29 13:53:23", "2033-05-17 18:03:20",
"2019-12-31 15:35:05", "2019-12-30 16:40:10", "2019-12-29 17:45:15",
"2009-12-30 18:50:20", "2009-12-31 19:55:25", "2010-01-02 21:00:30",
"2010-01-03 22:05:35", "2005-12-31 23:10:40", "2005-12-31 00:15:45",
"2008-12-27 14:30:00", "2008-12-28 14:30:00", "2011-12-31 15:32:03", null])";

for (auto u : TimeUnit::values()) {
CheckScalarUnary("local_time", timestamp(u), times_seconds_precision, timestamp(u),
times_seconds_precision);
CheckScalarUnary("local_time", timestamp(u, "UTC"), times_seconds_precision,
timestamp(u), times_seconds_precision);
CheckScalarUnary("local_time", timestamp(u, "Asia/Kolkata"), times_seconds_precision,
timestamp(u), expected_local_kolkata);
CheckScalarUnary("local_time", timestamp(u, "Pacific/Marquesas"),
times_seconds_precision, timestamp(u), expected_local_marquesas);
}
}

TEST_F(ScalarTemporalTest, TestAssumeTimezone) {
std::string timezone_utc = "UTC";
std::string timezone_kolkata = "Asia/Kolkata";
Expand Down
41 changes: 39 additions & 2 deletions cpp/src/arrow/compute/kernels/scalar_temporal_unary.cc
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Original file line numberDiff line numberDiff line change
Expand Up@@ -672,6 +672,23 @@ struct IsDaylightSavings {
const time_zone* tz_;
};

// ----------------------------------------------------------------------
// Extract local time of a given timestamp given its timezone

template <typename Duration, typename Localizer>
struct LocalTime {
explicit LocalTime(const FunctionOptions* options, Localizer&& localizer)
: localizer_(std::move(localizer)) {}

template <typename T, typename Arg0>
T Call(KernelContext*, Arg0 arg, Status*) const {
const auto t = localizer_.template ConvertTimePoint<Duration>(arg);
return static_cast<T>(t.time_since_epoch().count());
}

Localizer localizer_;
};

// ----------------------------------------------------------------------
// Round temporal values to given frequency

Expand DownExpand Up@@ -1327,6 +1344,12 @@ Result<TypeHolder> ResolveAssumeTimezoneOutput(KernelContext* ctx,
return timestamp(in_type.unit(), AssumeTimezoneState::Get(ctx).timezone);
}

Result<TypeHolder> ResolveLocalTimeOutput(KernelContext* ctx,
const std::vector<TypeHolder>& args) {
const auto& in_type = checked_cast<const TimestampType&>(*args[0]);
return timestamp(in_type.unit());
}

template <typename Duration>
struct AssumeTimezone {
explicit AssumeTimezone(const AssumeTimezoneOptions* options, const time_zone* tz)
Expand DownExpand Up@@ -1784,6 +1807,13 @@ const FunctionDoc is_dst_doc{
"An error is returned if the values do not have a defined timezone."),
{"values"}};

const FunctionDoc local_time_doc{
"Convert timestamp to a timezone-naive local time timestamp",
("LocalTime converts a timestamp to a local time of timestamps timezone\n"

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Something is missing in this sentence?

"and removes timezone metadata. If input is in UTC or doesn't have\n"
"timezone metadata, it is returned as is.\n"
Comment on lines +1813 to +1814

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Returned "as is" is not entirely correct for UTC, as I assume the "UTC" timezone is still removed?

"Null values emit null."),
{"values"}};
const FunctionDoc floor_temporal_doc{
"Round temporal values down to nearest multiple of specified time unit",
("Null values emit null.\n"
Expand All@@ -1801,8 +1831,9 @@ const FunctionDoc ceil_temporal_doc{
const FunctionDoc round_temporal_doc{
"Round temporal values to the nearest multiple of specified time unit",
("Null values emit null.\n"
"An error is returned if the values have a defined timezone but it\n"
"cannot be found in the timezone database."),
"If timezone is not given then timezone naive timestamp in UTC are\n"
"returned. An error is returned if the values have a defined timezone\n"
"but it cannot be found in the timezone database."),

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Was this change intentional? Or was it meant to be in local_time_doc?
(and if intentional, why only for round and not ceil/floor?)

{"timestamps"},
"RoundTemporalOptions"};

Expand DownExpand Up@@ -1969,6 +2000,12 @@ void RegisterScalarTemporalUnary(FunctionRegistry* registry) {
is_dst_doc);
DCHECK_OK(registry->AddFunction(std::move(is_dst)));

auto local_time =
UnaryTemporalFactory<LocalTime, TemporalComponentExtract, TimestampType>::Make<
WithTimestamps>("local_time", OutputType::Resolver(ResolveLocalTimeOutput),
local_time_doc);
DCHECK_OK(registry->AddFunction(std::move(local_time)));

// Temporal rounding functions
// Note: UnaryTemporalFactory will not correctly resolve OutputType(FirstType) to
// output type. See TemporalComponentExtractRound for more.
Expand Down
11 changes: 10 additions & 1 deletion docs/source/cpp/compute.rst
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Original file line numberDiff line numberDiff line change
Expand Up@@ -1545,7 +1545,7 @@ is the same, even though the UTC years would be different.
Timezone handling
~~~~~~~~~~~~~~~~~

This function is meant to be used when an external system produces
`assume_timezone` function is meant to be used when an external system produces
"timezone-naive" timestamps which need to be converted to "timezone-aware"
timestamps (see for example the `definition
<https://docs.python.org/3/library/datetime.html#aware-and-naive-objects>`__
Expand All@@ -1556,11 +1556,20 @@ Input timestamps are assumed to be relative to the timezone given in
UTC-relative timestamps with the timezone metadata set to the above value.
An error is returned if the timestamps already have the timezone metadata set.

`local_time` function converts UTC-relative timestamps to local "timezone-naive"
timestamps. The timezone is taken from the timezone metadata of the input
timestamps. This function is the inverse of `assume_timezone`. Please note:
**all temporal functions already operate on timestamps as if they were in local
time of the metadata provided timezone**. Using `local_time` is only meant to be
used when an external system expects local timestamps.

+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| Function name | Arity | Input types | Output type | Options class | Notes |
+====================+============+===================+===============+==================================+=======+
| assume_timezone | Unary | Timestamp | Timestamp | :struct:`AssumeTimezoneOptions` | \(1) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| local_time | Unary | Timestamp | Timestamp | | \(2) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+

* \(1) In addition to the timezone value, :struct:`AssumeTimezoneOptions`
allows choosing the behaviour when a timestamp is ambiguous or nonexistent
Expand Down
1 change: 1 addition & 0 deletions python/pyarrow/tests/test_compute.py
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Original file line numberDiff line numberDiff line change
Expand Up@@ -1951,6 +1951,7 @@ def _check_datetime_components(timestamps, timezone=None):
assert pc.microsecond(tsa).equals(pa.array(ts.dt.microsecond % 10 ** 3))
assert pc.nanosecond(tsa).equals(pa.array(ts.dt.nanosecond))
assert pc.subsecond(tsa).equals(pa.array(subseconds))
assert pc.local_time(tsa).equals(pa.array(ts.dt.tz_localize(None)))

if ts.dt.tz:
if ts.dt.tz is datetime.timezone.utc:
Expand Down
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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GH-33143: [C++] Kernel to convert timestamp with timezone to wall time#34208

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 Merged

westonpace
merged 4 commits into

from

Feb 17, 2023
 Merged


GH-33143: [C++] Kernel to convert timestamp with timezone to wall time
#34208
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8857c38

Adding local_time kernel


rok Feb 15, 2023
a5185a2

More test cases. Python tests.


rok Feb 16, 2023
115347e

Review feedback


rok Feb 17, 2023
cf2eb81

Apply suggestions from code review


rok Feb 17, 2023

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1 change: 1 addition & 0 deletions
cpp/src/arrow/compute/api_scalar.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -834,6 +834,7 @@ SCALAR_EAGER_UNARY(DayOfYear, "day_of_year")
SCALAR_EAGER_UNARY(Hour, "hour")
SCALAR_EAGER_UNARY(YearMonthDay, "year_month_day")
SCALAR_EAGER_UNARY(IsDaylightSavings, "is_dst")
SCALAR_EAGER_UNARY(LocalTime, "local_time")
SCALAR_EAGER_UNARY(IsLeapYear, "is_leap_year")
SCALAR_EAGER_UNARY(ISOCalendar, "iso_calendar")
SCALAR_EAGER_UNARY(ISOWeek, "iso_week")
Expand Down

10 changes: 10 additions & 0 deletions
cpp/src/arrow/compute/api_scalar.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1518,6 +1518,16 @@ ARROW_EXPORT Result<Datum> AssumeTimezone(const Datum& values,
ARROW_EXPORT Result<Datum> IsDaylightSavings(const Datum& values,
 ExecContext* ctx = NULLPTR);

/// \brief LocalTime converts timestamp to timezone naive local timestamp
///
/// \param[in] values input to convert to local time
/// \param[in] ctx the function execution context, optional
/// \return the resulting datum
///
/// \since 12.0.0
/// \note API not yet finalized
@westonpacewestonpaceFeb 17, 2023

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I was going to suggest removing this but now I see this is everywhere. Hmm.... :( I'm not sure how true this is these days.
@rokrokFeb 17, 2023

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Well, you could see it as an opportunity to sync the API with substrait :D
ARROW_EXPORT Result<Datum> LocalTime(const Datum& values, ExecContext* ctx = NULLPTR);

/// \brief Years Between finds the number of years between two values
///
/// \param[in] left input treated as the start time
Expand Down

33 changes: 33 additions & 0 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_test.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1811,6 +1811,39 @@ TEST_F(ScalarTemporalTest, TestTemporalDifferenceErrors) {
 CallFunction("weeks_between", {arr1, arr1}, &options));
}

TEST_F(ScalarTemporalTest, TestLocalTime) {
 const char* times_seconds_precision =
 R"(["1970-01-01T00:00:59", "2000-02-29T23:23:23", "2033-05-18T03:33:20",
 "2020-01-01T01:05:05", "2019-12-31T02:10:10", "2019-12-30T03:15:15",
 "2009-12-31T04:20:20", "2010-01-01T05:25:25", "2010-01-03T06:30:30",
 "2010-01-04T07:35:35", "2006-01-01T08:40:40", "2005-12-31T09:45:45",
 "2008-12-28", "2008-12-29", "2012-01-01 01:02:03", null])";

 const char* expected_local_kolkata =
 R"(["1970-01-01 05:30:59", "2000-03-01 04:53:23", "2033-05-18 09:03:20",
 "2020-01-01 06:35:05", "2019-12-31 07:40:10", "2019-12-30 08:45:15",
 "2009-12-31 09:50:20", "2010-01-01 10:55:25", "2010-01-03 12:00:30",
 "2010-01-04 13:05:35", "2006-01-01 14:10:40", "2005-12-31 15:15:45",
 "2008-12-28 05:30:00", "2008-12-29 05:30:00", "2012-01-01 06:32:03", null])";
 const char* expected_local_marquesas =
 R"(["1969-12-31 14:30:59", "2000-02-29 13:53:23", "2033-05-17 18:03:20",
 "2019-12-31 15:35:05", "2019-12-30 16:40:10", "2019-12-29 17:45:15",
 "2009-12-30 18:50:20", "2009-12-31 19:55:25", "2010-01-02 21:00:30",
 "2010-01-03 22:05:35", "2005-12-31 23:10:40", "2005-12-31 00:15:45",
 "2008-12-27 14:30:00", "2008-12-28 14:30:00", "2011-12-31 15:32:03", null])";

 for (auto u : TimeUnit::values()) {
 CheckScalarUnary("local_time", timestamp(u), times_seconds_precision, timestamp(u),
 times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "UTC"), times_seconds_precision,
 timestamp(u), times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "Asia/Kolkata"), times_seconds_precision,
 timestamp(u), expected_local_kolkata);
 CheckScalarUnary("local_time", timestamp(u, "Pacific/Marquesas"),
 times_seconds_precision, timestamp(u), expected_local_marquesas);
 }
}

TEST_F(ScalarTemporalTest, TestAssumeTimezone) {
 std::string timezone_utc = "UTC";
 std::string timezone_kolkata = "Asia/Kolkata";
Expand Down

41 changes: 39 additions & 2 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_unary.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -672,6 +672,23 @@ struct IsDaylightSavings {
 const time_zone* tz_;
};

// ----------------------------------------------------------------------
// Extract local time of a given timestamp given its timezone

template <typename Duration, typename Localizer>
struct LocalTime {
 explicit LocalTime(const FunctionOptions* options, Localizer&& localizer)
 : localizer_(std::move(localizer)) {}

 template <typename T, typename Arg0>
 T Call(KernelContext*, Arg0 arg, Status*) const {
 const auto t = localizer_.template ConvertTimePoint<Duration>(arg);
 return static_cast<T>(t.time_since_epoch().count());
 }

 Localizer localizer_;
};

// ----------------------------------------------------------------------
// Round temporal values to given frequency

Expand DownExpand Up@@ -1327,6 +1344,12 @@ Result<TypeHolder> ResolveAssumeTimezoneOutput(KernelContext* ctx,
 return timestamp(in_type.unit(), AssumeTimezoneState::Get(ctx).timezone);
}

Result<TypeHolder> ResolveLocalTimeOutput(KernelContext* ctx,
 const std::vector<TypeHolder>& args) {
 const auto& in_type = checked_cast<const TimestampType&>(*args[0]);
 return timestamp(in_type.unit());
}

template <typename Duration>
struct AssumeTimezone {
 explicit AssumeTimezone(const AssumeTimezoneOptions* options, const time_zone* tz)
Expand DownExpand Up@@ -1784,6 +1807,13 @@ const FunctionDoc is_dst_doc{
 "An error is returned if the values do not have a defined timezone."),
 {"values"}};

const FunctionDoc local_time_doc{
 "Convert timestamp to a timezone-naive local time timestamp",
 ("LocalTime converts a timestamp to a local time of timestamps timezone\n"
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Something is missing in this sentence?
 "and removes timezone metadata. If input is in UTC or doesn't have\n"
 "timezone metadata, it is returned as is.\n"

Comment on lines

+1813
 to 
+1814

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Returned "as is" is not entirely correct for UTC, as I assume the "UTC" timezone is still removed?
 "Null values emit null."),
 {"values"}};
const FunctionDoc floor_temporal_doc{
 "Round temporal values down to nearest multiple of specified time unit",
 ("Null values emit null.\n"
Expand All@@ -1801,8 +1831,9 @@ const FunctionDoc ceil_temporal_doc{
const FunctionDoc round_temporal_doc{
 "Round temporal values to the nearest multiple of specified time unit",
 ("Null values emit null.\n"
 "An error is returned if the values have a defined timezone but it\n"
 "cannot be found in the timezone database."),
 "If timezone is not given then timezone naive timestamp in UTC are\n"
 "returned. An error is returned if the values have a defined timezone\n"
 "but it cannot be found in the timezone database."),
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Was this change intentional? Or was it meant to be in local_time_doc?

(and if intentional, why only for round and not ceil/floor?)
 {"timestamps"},
 "RoundTemporalOptions"};

Expand DownExpand Up@@ -1969,6 +2000,12 @@ void RegisterScalarTemporalUnary(FunctionRegistry* registry) {
 is_dst_doc);
 DCHECK_OK(registry->AddFunction(std::move(is_dst)));

 auto local_time =
 UnaryTemporalFactory<LocalTime, TemporalComponentExtract, TimestampType>::Make<
 WithTimestamps>("local_time", OutputType::Resolver(ResolveLocalTimeOutput),
 local_time_doc);
 DCHECK_OK(registry->AddFunction(std::move(local_time)));

 // Temporal rounding functions
 // Note: UnaryTemporalFactory will not correctly resolve OutputType(FirstType) to
 // output type. See TemporalComponentExtractRound for more.
Expand Down

11 changes: 10 additions & 1 deletion
docs/source/cpp/compute.rst

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1545,7 +1545,7 @@ is the same, even though the UTC years would be different.
Timezone handling
~~~~~~~~~~~~~~~~~

This function is meant to be used when an external system produces
`assume_timezone` function is meant to be used when an external system produces
"timezone-naive" timestamps which need to be converted to "timezone-aware"
timestamps (see for example the `definition
<https://docs.python.org/3/library/datetime.html#aware-and-naive-objects>`__
Expand All@@ -1556,11 +1556,20 @@ Input timestamps are assumed to be relative to the timezone given in
UTC-relative timestamps with the timezone metadata set to the above value.
An error is returned if the timestamps already have the timezone metadata set.

`local_time` function converts UTC-relative timestamps to local "timezone-naive"
timestamps. The timezone is taken from the timezone metadata of the input
timestamps. This function is the inverse of `assume_timezone`. Please note:
**all temporal functions already operate on timestamps as if they were in local
time of the metadata provided timezone**. Using `local_time` is only meant to be
used when an external system expects local timestamps.

+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| Function name | Arity | Input types | Output type | Options class | Notes |
+====================+============+===================+===============+==================================+=======+
| assume_timezone | Unary | Timestamp | Timestamp | :struct:`AssumeTimezoneOptions` | \(1) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| local_time | Unary | Timestamp | Timestamp | | \(2) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+

* \(1) In addition to the timezone value, :struct:`AssumeTimezoneOptions`
 allows choosing the behaviour when a timestamp is ambiguous or nonexistent
Expand Down

1 change: 1 addition & 0 deletions
python/pyarrow/tests/test_compute.py

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1951,6 +1951,7 @@ def _check_datetime_components(timestamps, timezone=None):
 assert pc.microsecond(tsa).equals(pa.array(ts.dt.microsecond % 10 ** 3))
 assert pc.nanosecond(tsa).equals(pa.array(ts.dt.nanosecond))
 assert pc.subsecond(tsa).equals(pa.array(subseconds))
 assert pc.local_time(tsa).equals(pa.array(ts.dt.tz_localize(None)))

 if ts.dt.tz:
 if ts.dt.tz is datetime.timezone.utc:
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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GH-33143: [C++] Kernel to convert timestamp with timezone to wall time#34208

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westonpace
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Feb 17, 2023
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GH-33143: [C++] Kernel to convert timestamp with timezone to wall time
#34208
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8857c38

Adding local_time kernel


rok Feb 15, 2023
a5185a2

More test cases. Python tests.


rok Feb 16, 2023
115347e

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1 change: 1 addition & 0 deletions
cpp/src/arrow/compute/api_scalar.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -834,6 +834,7 @@ SCALAR_EAGER_UNARY(DayOfYear, "day_of_year")
SCALAR_EAGER_UNARY(Hour, "hour")
SCALAR_EAGER_UNARY(YearMonthDay, "year_month_day")
SCALAR_EAGER_UNARY(IsDaylightSavings, "is_dst")
SCALAR_EAGER_UNARY(LocalTime, "local_time")
SCALAR_EAGER_UNARY(IsLeapYear, "is_leap_year")
SCALAR_EAGER_UNARY(ISOCalendar, "iso_calendar")
SCALAR_EAGER_UNARY(ISOWeek, "iso_week")
Expand Down

10 changes: 10 additions & 0 deletions
cpp/src/arrow/compute/api_scalar.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1518,6 +1518,16 @@ ARROW_EXPORT Result<Datum> AssumeTimezone(const Datum& values,
ARROW_EXPORT Result<Datum> IsDaylightSavings(const Datum& values,
 ExecContext* ctx = NULLPTR);

/// \brief LocalTime converts timestamp to timezone naive local timestamp
///
/// \param[in] values input to convert to local time
/// \param[in] ctx the function execution context, optional
/// \return the resulting datum
///
/// \since 12.0.0
/// \note API not yet finalized
@westonpacewestonpaceFeb 17, 2023

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I was going to suggest removing this but now I see this is everywhere. Hmm.... :( I'm not sure how true this is these days.
@rokrokFeb 17, 2023

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Well, you could see it as an opportunity to sync the API with substrait :D
ARROW_EXPORT Result<Datum> LocalTime(const Datum& values, ExecContext* ctx = NULLPTR);

/// \brief Years Between finds the number of years between two values
///
/// \param[in] left input treated as the start time
Expand Down

33 changes: 33 additions & 0 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_test.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1811,6 +1811,39 @@ TEST_F(ScalarTemporalTest, TestTemporalDifferenceErrors) {
 CallFunction("weeks_between", {arr1, arr1}, &options));
}

TEST_F(ScalarTemporalTest, TestLocalTime) {
 const char* times_seconds_precision =
 R"(["1970-01-01T00:00:59", "2000-02-29T23:23:23", "2033-05-18T03:33:20",
 "2020-01-01T01:05:05", "2019-12-31T02:10:10", "2019-12-30T03:15:15",
 "2009-12-31T04:20:20", "2010-01-01T05:25:25", "2010-01-03T06:30:30",
 "2010-01-04T07:35:35", "2006-01-01T08:40:40", "2005-12-31T09:45:45",
 "2008-12-28", "2008-12-29", "2012-01-01 01:02:03", null])";

 const char* expected_local_kolkata =
 R"(["1970-01-01 05:30:59", "2000-03-01 04:53:23", "2033-05-18 09:03:20",
 "2020-01-01 06:35:05", "2019-12-31 07:40:10", "2019-12-30 08:45:15",
 "2009-12-31 09:50:20", "2010-01-01 10:55:25", "2010-01-03 12:00:30",
 "2010-01-04 13:05:35", "2006-01-01 14:10:40", "2005-12-31 15:15:45",
 "2008-12-28 05:30:00", "2008-12-29 05:30:00", "2012-01-01 06:32:03", null])";
 const char* expected_local_marquesas =
 R"(["1969-12-31 14:30:59", "2000-02-29 13:53:23", "2033-05-17 18:03:20",
 "2019-12-31 15:35:05", "2019-12-30 16:40:10", "2019-12-29 17:45:15",
 "2009-12-30 18:50:20", "2009-12-31 19:55:25", "2010-01-02 21:00:30",
 "2010-01-03 22:05:35", "2005-12-31 23:10:40", "2005-12-31 00:15:45",
 "2008-12-27 14:30:00", "2008-12-28 14:30:00", "2011-12-31 15:32:03", null])";

 for (auto u : TimeUnit::values()) {
 CheckScalarUnary("local_time", timestamp(u), times_seconds_precision, timestamp(u),
 times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "UTC"), times_seconds_precision,
 timestamp(u), times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "Asia/Kolkata"), times_seconds_precision,
 timestamp(u), expected_local_kolkata);
 CheckScalarUnary("local_time", timestamp(u, "Pacific/Marquesas"),
 times_seconds_precision, timestamp(u), expected_local_marquesas);
 }
}

TEST_F(ScalarTemporalTest, TestAssumeTimezone) {
 std::string timezone_utc = "UTC";
 std::string timezone_kolkata = "Asia/Kolkata";
Expand Down

41 changes: 39 additions & 2 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_unary.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -672,6 +672,23 @@ struct IsDaylightSavings {
 const time_zone* tz_;
};

// ----------------------------------------------------------------------
// Extract local time of a given timestamp given its timezone

template <typename Duration, typename Localizer>
struct LocalTime {
 explicit LocalTime(const FunctionOptions* options, Localizer&& localizer)
 : localizer_(std::move(localizer)) {}

 template <typename T, typename Arg0>
 T Call(KernelContext*, Arg0 arg, Status*) const {
 const auto t = localizer_.template ConvertTimePoint<Duration>(arg);
 return static_cast<T>(t.time_since_epoch().count());
 }

 Localizer localizer_;
};

// ----------------------------------------------------------------------
// Round temporal values to given frequency

Expand DownExpand Up@@ -1327,6 +1344,12 @@ Result<TypeHolder> ResolveAssumeTimezoneOutput(KernelContext* ctx,
 return timestamp(in_type.unit(), AssumeTimezoneState::Get(ctx).timezone);
}

Result<TypeHolder> ResolveLocalTimeOutput(KernelContext* ctx,
 const std::vector<TypeHolder>& args) {
 const auto& in_type = checked_cast<const TimestampType&>(*args[0]);
 return timestamp(in_type.unit());
}

template <typename Duration>
struct AssumeTimezone {
 explicit AssumeTimezone(const AssumeTimezoneOptions* options, const time_zone* tz)
Expand DownExpand Up@@ -1784,6 +1807,13 @@ const FunctionDoc is_dst_doc{
 "An error is returned if the values do not have a defined timezone."),
 {"values"}};

const FunctionDoc local_time_doc{
 "Convert timestamp to a timezone-naive local time timestamp",
 ("LocalTime converts a timestamp to a local time of timestamps timezone\n"
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Something is missing in this sentence?
 "and removes timezone metadata. If input is in UTC or doesn't have\n"
 "timezone metadata, it is returned as is.\n"

Comment on lines

+1813
 to 
+1814

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Returned "as is" is not entirely correct for UTC, as I assume the "UTC" timezone is still removed?
 "Null values emit null."),
 {"values"}};
const FunctionDoc floor_temporal_doc{
 "Round temporal values down to nearest multiple of specified time unit",
 ("Null values emit null.\n"
Expand All@@ -1801,8 +1831,9 @@ const FunctionDoc ceil_temporal_doc{
const FunctionDoc round_temporal_doc{
 "Round temporal values to the nearest multiple of specified time unit",
 ("Null values emit null.\n"
 "An error is returned if the values have a defined timezone but it\n"
 "cannot be found in the timezone database."),
 "If timezone is not given then timezone naive timestamp in UTC are\n"
 "returned. An error is returned if the values have a defined timezone\n"
 "but it cannot be found in the timezone database."),
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Was this change intentional? Or was it meant to be in local_time_doc?

(and if intentional, why only for round and not ceil/floor?)
 {"timestamps"},
 "RoundTemporalOptions"};

Expand DownExpand Up@@ -1969,6 +2000,12 @@ void RegisterScalarTemporalUnary(FunctionRegistry* registry) {
 is_dst_doc);
 DCHECK_OK(registry->AddFunction(std::move(is_dst)));

 auto local_time =
 UnaryTemporalFactory<LocalTime, TemporalComponentExtract, TimestampType>::Make<
 WithTimestamps>("local_time", OutputType::Resolver(ResolveLocalTimeOutput),
 local_time_doc);
 DCHECK_OK(registry->AddFunction(std::move(local_time)));

 // Temporal rounding functions
 // Note: UnaryTemporalFactory will not correctly resolve OutputType(FirstType) to
 // output type. See TemporalComponentExtractRound for more.
Expand Down

11 changes: 10 additions & 1 deletion
docs/source/cpp/compute.rst

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1545,7 +1545,7 @@ is the same, even though the UTC years would be different.
Timezone handling
~~~~~~~~~~~~~~~~~

This function is meant to be used when an external system produces
`assume_timezone` function is meant to be used when an external system produces
"timezone-naive" timestamps which need to be converted to "timezone-aware"
timestamps (see for example the `definition
<https://docs.python.org/3/library/datetime.html#aware-and-naive-objects>`__
Expand All@@ -1556,11 +1556,20 @@ Input timestamps are assumed to be relative to the timezone given in
UTC-relative timestamps with the timezone metadata set to the above value.
An error is returned if the timestamps already have the timezone metadata set.

`local_time` function converts UTC-relative timestamps to local "timezone-naive"
timestamps. The timezone is taken from the timezone metadata of the input
timestamps. This function is the inverse of `assume_timezone`. Please note:
**all temporal functions already operate on timestamps as if they were in local
time of the metadata provided timezone**. Using `local_time` is only meant to be
used when an external system expects local timestamps.

+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| Function name | Arity | Input types | Output type | Options class | Notes |
+====================+============+===================+===============+==================================+=======+
| assume_timezone | Unary | Timestamp | Timestamp | :struct:`AssumeTimezoneOptions` | \(1) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| local_time | Unary | Timestamp | Timestamp | | \(2) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+

* \(1) In addition to the timezone value, :struct:`AssumeTimezoneOptions`
 allows choosing the behaviour when a timestamp is ambiguous or nonexistent
Expand Down

1 change: 1 addition & 0 deletions
python/pyarrow/tests/test_compute.py

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1951,6 +1951,7 @@ def _check_datetime_components(timestamps, timezone=None):
 assert pc.microsecond(tsa).equals(pa.array(ts.dt.microsecond % 10 ** 3))
 assert pc.nanosecond(tsa).equals(pa.array(ts.dt.nanosecond))
 assert pc.subsecond(tsa).equals(pa.array(subseconds))
 assert pc.local_time(tsa).equals(pa.array(ts.dt.tz_localize(None)))

 if ts.dt.tz:
 if ts.dt.tz is datetime.timezone.utc:
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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GH-33143: [C++] Kernel to convert timestamp with timezone to wall time#34208

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 Merged

westonpace
merged 4 commits into

from

Feb 17, 2023
 Merged


GH-33143: [C++] Kernel to convert timestamp with timezone to wall time
#34208
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8857c38

Adding local_time kernel


rok Feb 15, 2023
a5185a2

More test cases. Python tests.


rok Feb 16, 2023
115347e

Review feedback


rok Feb 17, 2023
cf2eb81

Apply suggestions from code review


rok Feb 17, 2023

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cpp/src/arrow/compute/api_scalar.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -834,6 +834,7 @@ SCALAR_EAGER_UNARY(DayOfYear, "day_of_year")
SCALAR_EAGER_UNARY(Hour, "hour")
SCALAR_EAGER_UNARY(YearMonthDay, "year_month_day")
SCALAR_EAGER_UNARY(IsDaylightSavings, "is_dst")
SCALAR_EAGER_UNARY(LocalTime, "local_time")
SCALAR_EAGER_UNARY(IsLeapYear, "is_leap_year")
SCALAR_EAGER_UNARY(ISOCalendar, "iso_calendar")
SCALAR_EAGER_UNARY(ISOWeek, "iso_week")
Expand Down

10 changes: 10 additions & 0 deletions
cpp/src/arrow/compute/api_scalar.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1518,6 +1518,16 @@ ARROW_EXPORT Result<Datum> AssumeTimezone(const Datum& values,
ARROW_EXPORT Result<Datum> IsDaylightSavings(const Datum& values,
 ExecContext* ctx = NULLPTR);

/// \brief LocalTime converts timestamp to timezone naive local timestamp
///
/// \param[in] values input to convert to local time
/// \param[in] ctx the function execution context, optional
/// \return the resulting datum
///
/// \since 12.0.0
/// \note API not yet finalized
@westonpacewestonpaceFeb 17, 2023

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I was going to suggest removing this but now I see this is everywhere. Hmm.... :( I'm not sure how true this is these days.
@rokrokFeb 17, 2023

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Well, you could see it as an opportunity to sync the API with substrait :D
ARROW_EXPORT Result<Datum> LocalTime(const Datum& values, ExecContext* ctx = NULLPTR);

/// \brief Years Between finds the number of years between two values
///
/// \param[in] left input treated as the start time
Expand Down

33 changes: 33 additions & 0 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_test.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1811,6 +1811,39 @@ TEST_F(ScalarTemporalTest, TestTemporalDifferenceErrors) {
 CallFunction("weeks_between", {arr1, arr1}, &options));
}

TEST_F(ScalarTemporalTest, TestLocalTime) {
 const char* times_seconds_precision =
 R"(["1970-01-01T00:00:59", "2000-02-29T23:23:23", "2033-05-18T03:33:20",
 "2020-01-01T01:05:05", "2019-12-31T02:10:10", "2019-12-30T03:15:15",
 "2009-12-31T04:20:20", "2010-01-01T05:25:25", "2010-01-03T06:30:30",
 "2010-01-04T07:35:35", "2006-01-01T08:40:40", "2005-12-31T09:45:45",
 "2008-12-28", "2008-12-29", "2012-01-01 01:02:03", null])";

 const char* expected_local_kolkata =
 R"(["1970-01-01 05:30:59", "2000-03-01 04:53:23", "2033-05-18 09:03:20",
 "2020-01-01 06:35:05", "2019-12-31 07:40:10", "2019-12-30 08:45:15",
 "2009-12-31 09:50:20", "2010-01-01 10:55:25", "2010-01-03 12:00:30",
 "2010-01-04 13:05:35", "2006-01-01 14:10:40", "2005-12-31 15:15:45",
 "2008-12-28 05:30:00", "2008-12-29 05:30:00", "2012-01-01 06:32:03", null])";
 const char* expected_local_marquesas =
 R"(["1969-12-31 14:30:59", "2000-02-29 13:53:23", "2033-05-17 18:03:20",
 "2019-12-31 15:35:05", "2019-12-30 16:40:10", "2019-12-29 17:45:15",
 "2009-12-30 18:50:20", "2009-12-31 19:55:25", "2010-01-02 21:00:30",
 "2010-01-03 22:05:35", "2005-12-31 23:10:40", "2005-12-31 00:15:45",
 "2008-12-27 14:30:00", "2008-12-28 14:30:00", "2011-12-31 15:32:03", null])";

 for (auto u : TimeUnit::values()) {
 CheckScalarUnary("local_time", timestamp(u), times_seconds_precision, timestamp(u),
 times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "UTC"), times_seconds_precision,
 timestamp(u), times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "Asia/Kolkata"), times_seconds_precision,
 timestamp(u), expected_local_kolkata);
 CheckScalarUnary("local_time", timestamp(u, "Pacific/Marquesas"),
 times_seconds_precision, timestamp(u), expected_local_marquesas);
 }
}

TEST_F(ScalarTemporalTest, TestAssumeTimezone) {
 std::string timezone_utc = "UTC";
 std::string timezone_kolkata = "Asia/Kolkata";
Expand Down

41 changes: 39 additions & 2 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_unary.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -672,6 +672,23 @@ struct IsDaylightSavings {
 const time_zone* tz_;
};

// ----------------------------------------------------------------------
// Extract local time of a given timestamp given its timezone

template <typename Duration, typename Localizer>
struct LocalTime {
 explicit LocalTime(const FunctionOptions* options, Localizer&& localizer)
 : localizer_(std::move(localizer)) {}

 template <typename T, typename Arg0>
 T Call(KernelContext*, Arg0 arg, Status*) const {
 const auto t = localizer_.template ConvertTimePoint<Duration>(arg);
 return static_cast<T>(t.time_since_epoch().count());
 }

 Localizer localizer_;
};

// ----------------------------------------------------------------------
// Round temporal values to given frequency

Expand DownExpand Up@@ -1327,6 +1344,12 @@ Result<TypeHolder> ResolveAssumeTimezoneOutput(KernelContext* ctx,
 return timestamp(in_type.unit(), AssumeTimezoneState::Get(ctx).timezone);
}

Result<TypeHolder> ResolveLocalTimeOutput(KernelContext* ctx,
 const std::vector<TypeHolder>& args) {
 const auto& in_type = checked_cast<const TimestampType&>(*args[0]);
 return timestamp(in_type.unit());
}

template <typename Duration>
struct AssumeTimezone {
 explicit AssumeTimezone(const AssumeTimezoneOptions* options, const time_zone* tz)
Expand DownExpand Up@@ -1784,6 +1807,13 @@ const FunctionDoc is_dst_doc{
 "An error is returned if the values do not have a defined timezone."),
 {"values"}};

const FunctionDoc local_time_doc{
 "Convert timestamp to a timezone-naive local time timestamp",
 ("LocalTime converts a timestamp to a local time of timestamps timezone\n"
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Something is missing in this sentence?
 "and removes timezone metadata. If input is in UTC or doesn't have\n"
 "timezone metadata, it is returned as is.\n"

Comment on lines

+1813
 to 
+1814

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Returned "as is" is not entirely correct for UTC, as I assume the "UTC" timezone is still removed?
 "Null values emit null."),
 {"values"}};
const FunctionDoc floor_temporal_doc{
 "Round temporal values down to nearest multiple of specified time unit",
 ("Null values emit null.\n"
Expand All@@ -1801,8 +1831,9 @@ const FunctionDoc ceil_temporal_doc{
const FunctionDoc round_temporal_doc{
 "Round temporal values to the nearest multiple of specified time unit",
 ("Null values emit null.\n"
 "An error is returned if the values have a defined timezone but it\n"
 "cannot be found in the timezone database."),
 "If timezone is not given then timezone naive timestamp in UTC are\n"
 "returned. An error is returned if the values have a defined timezone\n"
 "but it cannot be found in the timezone database."),
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Was this change intentional? Or was it meant to be in local_time_doc?

(and if intentional, why only for round and not ceil/floor?)
 {"timestamps"},
 "RoundTemporalOptions"};

Expand DownExpand Up@@ -1969,6 +2000,12 @@ void RegisterScalarTemporalUnary(FunctionRegistry* registry) {
 is_dst_doc);
 DCHECK_OK(registry->AddFunction(std::move(is_dst)));

 auto local_time =
 UnaryTemporalFactory<LocalTime, TemporalComponentExtract, TimestampType>::Make<
 WithTimestamps>("local_time", OutputType::Resolver(ResolveLocalTimeOutput),
 local_time_doc);
 DCHECK_OK(registry->AddFunction(std::move(local_time)));

 // Temporal rounding functions
 // Note: UnaryTemporalFactory will not correctly resolve OutputType(FirstType) to
 // output type. See TemporalComponentExtractRound for more.
Expand Down

11 changes: 10 additions & 1 deletion
docs/source/cpp/compute.rst

View file


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Original file line numberDiff line numberDiff line change
Expand Up@@ -1545,7 +1545,7 @@ is the same, even though the UTC years would be different.
Timezone handling
~~~~~~~~~~~~~~~~~

This function is meant to be used when an external system produces
`assume_timezone` function is meant to be used when an external system produces
"timezone-naive" timestamps which need to be converted to "timezone-aware"
timestamps (see for example the `definition
<https://docs.python.org/3/library/datetime.html#aware-and-naive-objects>`__
Expand All@@ -1556,11 +1556,20 @@ Input timestamps are assumed to be relative to the timezone given in
UTC-relative timestamps with the timezone metadata set to the above value.
An error is returned if the timestamps already have the timezone metadata set.

`local_time` function converts UTC-relative timestamps to local "timezone-naive"
timestamps. The timezone is taken from the timezone metadata of the input
timestamps. This function is the inverse of `assume_timezone`. Please note:
**all temporal functions already operate on timestamps as if they were in local
time of the metadata provided timezone**. Using `local_time` is only meant to be
used when an external system expects local timestamps.

+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| Function name | Arity | Input types | Output type | Options class | Notes |
+====================+============+===================+===============+==================================+=======+
| assume_timezone | Unary | Timestamp | Timestamp | :struct:`AssumeTimezoneOptions` | \(1) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| local_time | Unary | Timestamp | Timestamp | | \(2) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+

* \(1) In addition to the timezone value, :struct:`AssumeTimezoneOptions`
 allows choosing the behaviour when a timestamp is ambiguous or nonexistent
Expand Down

1 change: 1 addition & 0 deletions
python/pyarrow/tests/test_compute.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1951,6 +1951,7 @@ def _check_datetime_components(timestamps, timezone=None):
 assert pc.microsecond(tsa).equals(pa.array(ts.dt.microsecond % 10 ** 3))
 assert pc.nanosecond(tsa).equals(pa.array(ts.dt.nanosecond))
 assert pc.subsecond(tsa).equals(pa.array(subseconds))
 assert pc.local_time(tsa).equals(pa.array(ts.dt.tz_localize(None)))

 if ts.dt.tz:
 if ts.dt.tz is datetime.timezone.utc:
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

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GH-33143: [C++] Kernel to convert timestamp with timezone to wall time#34208

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westonpace
merged 4 commits into

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Feb 17, 2023
 Merged


GH-33143: [C++] Kernel to convert timestamp with timezone to wall time
#34208
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8857c38

Adding local_time kernel


rok Feb 15, 2023
a5185a2

More test cases. Python tests.


rok Feb 16, 2023
115347e

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cf2eb81

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1 change: 1 addition & 0 deletions
cpp/src/arrow/compute/api_scalar.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -834,6 +834,7 @@ SCALAR_EAGER_UNARY(DayOfYear, "day_of_year")
SCALAR_EAGER_UNARY(Hour, "hour")
SCALAR_EAGER_UNARY(YearMonthDay, "year_month_day")
SCALAR_EAGER_UNARY(IsDaylightSavings, "is_dst")
SCALAR_EAGER_UNARY(LocalTime, "local_time")
SCALAR_EAGER_UNARY(IsLeapYear, "is_leap_year")
SCALAR_EAGER_UNARY(ISOCalendar, "iso_calendar")
SCALAR_EAGER_UNARY(ISOWeek, "iso_week")
Expand Down

10 changes: 10 additions & 0 deletions
cpp/src/arrow/compute/api_scalar.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1518,6 +1518,16 @@ ARROW_EXPORT Result<Datum> AssumeTimezone(const Datum& values,
ARROW_EXPORT Result<Datum> IsDaylightSavings(const Datum& values,
 ExecContext* ctx = NULLPTR);

/// \brief LocalTime converts timestamp to timezone naive local timestamp
///
/// \param[in] values input to convert to local time
/// \param[in] ctx the function execution context, optional
/// \return the resulting datum
///
/// \since 12.0.0
/// \note API not yet finalized
@westonpacewestonpaceFeb 17, 2023

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I was going to suggest removing this but now I see this is everywhere. Hmm.... :( I'm not sure how true this is these days.
@rokrokFeb 17, 2023

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Well, you could see it as an opportunity to sync the API with substrait :D
ARROW_EXPORT Result<Datum> LocalTime(const Datum& values, ExecContext* ctx = NULLPTR);

/// \brief Years Between finds the number of years between two values
///
/// \param[in] left input treated as the start time
Expand Down

33 changes: 33 additions & 0 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_test.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1811,6 +1811,39 @@ TEST_F(ScalarTemporalTest, TestTemporalDifferenceErrors) {
 CallFunction("weeks_between", {arr1, arr1}, &options));
}

TEST_F(ScalarTemporalTest, TestLocalTime) {
 const char* times_seconds_precision =
 R"(["1970-01-01T00:00:59", "2000-02-29T23:23:23", "2033-05-18T03:33:20",
 "2020-01-01T01:05:05", "2019-12-31T02:10:10", "2019-12-30T03:15:15",
 "2009-12-31T04:20:20", "2010-01-01T05:25:25", "2010-01-03T06:30:30",
 "2010-01-04T07:35:35", "2006-01-01T08:40:40", "2005-12-31T09:45:45",
 "2008-12-28", "2008-12-29", "2012-01-01 01:02:03", null])";

 const char* expected_local_kolkata =
 R"(["1970-01-01 05:30:59", "2000-03-01 04:53:23", "2033-05-18 09:03:20",
 "2020-01-01 06:35:05", "2019-12-31 07:40:10", "2019-12-30 08:45:15",
 "2009-12-31 09:50:20", "2010-01-01 10:55:25", "2010-01-03 12:00:30",
 "2010-01-04 13:05:35", "2006-01-01 14:10:40", "2005-12-31 15:15:45",
 "2008-12-28 05:30:00", "2008-12-29 05:30:00", "2012-01-01 06:32:03", null])";
 const char* expected_local_marquesas =
 R"(["1969-12-31 14:30:59", "2000-02-29 13:53:23", "2033-05-17 18:03:20",
 "2019-12-31 15:35:05", "2019-12-30 16:40:10", "2019-12-29 17:45:15",
 "2009-12-30 18:50:20", "2009-12-31 19:55:25", "2010-01-02 21:00:30",
 "2010-01-03 22:05:35", "2005-12-31 23:10:40", "2005-12-31 00:15:45",
 "2008-12-27 14:30:00", "2008-12-28 14:30:00", "2011-12-31 15:32:03", null])";

 for (auto u : TimeUnit::values()) {
 CheckScalarUnary("local_time", timestamp(u), times_seconds_precision, timestamp(u),
 times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "UTC"), times_seconds_precision,
 timestamp(u), times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "Asia/Kolkata"), times_seconds_precision,
 timestamp(u), expected_local_kolkata);
 CheckScalarUnary("local_time", timestamp(u, "Pacific/Marquesas"),
 times_seconds_precision, timestamp(u), expected_local_marquesas);
 }
}

TEST_F(ScalarTemporalTest, TestAssumeTimezone) {
 std::string timezone_utc = "UTC";
 std::string timezone_kolkata = "Asia/Kolkata";
Expand Down

41 changes: 39 additions & 2 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_unary.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -672,6 +672,23 @@ struct IsDaylightSavings {
 const time_zone* tz_;
};

// ----------------------------------------------------------------------
// Extract local time of a given timestamp given its timezone

template <typename Duration, typename Localizer>
struct LocalTime {
 explicit LocalTime(const FunctionOptions* options, Localizer&& localizer)
 : localizer_(std::move(localizer)) {}

 template <typename T, typename Arg0>
 T Call(KernelContext*, Arg0 arg, Status*) const {
 const auto t = localizer_.template ConvertTimePoint<Duration>(arg);
 return static_cast<T>(t.time_since_epoch().count());
 }

 Localizer localizer_;
};

// ----------------------------------------------------------------------
// Round temporal values to given frequency

Expand DownExpand Up@@ -1327,6 +1344,12 @@ Result<TypeHolder> ResolveAssumeTimezoneOutput(KernelContext* ctx,
 return timestamp(in_type.unit(), AssumeTimezoneState::Get(ctx).timezone);
}

Result<TypeHolder> ResolveLocalTimeOutput(KernelContext* ctx,
 const std::vector<TypeHolder>& args) {
 const auto& in_type = checked_cast<const TimestampType&>(*args[0]);
 return timestamp(in_type.unit());
}

template <typename Duration>
struct AssumeTimezone {
 explicit AssumeTimezone(const AssumeTimezoneOptions* options, const time_zone* tz)
Expand DownExpand Up@@ -1784,6 +1807,13 @@ const FunctionDoc is_dst_doc{
 "An error is returned if the values do not have a defined timezone."),
 {"values"}};

const FunctionDoc local_time_doc{
 "Convert timestamp to a timezone-naive local time timestamp",
 ("LocalTime converts a timestamp to a local time of timestamps timezone\n"
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Something is missing in this sentence?
 "and removes timezone metadata. If input is in UTC or doesn't have\n"
 "timezone metadata, it is returned as is.\n"

Comment on lines

+1813
 to 
+1814

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Returned "as is" is not entirely correct for UTC, as I assume the "UTC" timezone is still removed?
 "Null values emit null."),
 {"values"}};
const FunctionDoc floor_temporal_doc{
 "Round temporal values down to nearest multiple of specified time unit",
 ("Null values emit null.\n"
Expand All@@ -1801,8 +1831,9 @@ const FunctionDoc ceil_temporal_doc{
const FunctionDoc round_temporal_doc{
 "Round temporal values to the nearest multiple of specified time unit",
 ("Null values emit null.\n"
 "An error is returned if the values have a defined timezone but it\n"
 "cannot be found in the timezone database."),
 "If timezone is not given then timezone naive timestamp in UTC are\n"
 "returned. An error is returned if the values have a defined timezone\n"
 "but it cannot be found in the timezone database."),
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Was this change intentional? Or was it meant to be in local_time_doc?

(and if intentional, why only for round and not ceil/floor?)
 {"timestamps"},
 "RoundTemporalOptions"};

Expand DownExpand Up@@ -1969,6 +2000,12 @@ void RegisterScalarTemporalUnary(FunctionRegistry* registry) {
 is_dst_doc);
 DCHECK_OK(registry->AddFunction(std::move(is_dst)));

 auto local_time =
 UnaryTemporalFactory<LocalTime, TemporalComponentExtract, TimestampType>::Make<
 WithTimestamps>("local_time", OutputType::Resolver(ResolveLocalTimeOutput),
 local_time_doc);
 DCHECK_OK(registry->AddFunction(std::move(local_time)));

 // Temporal rounding functions
 // Note: UnaryTemporalFactory will not correctly resolve OutputType(FirstType) to
 // output type. See TemporalComponentExtractRound for more.
Expand Down

11 changes: 10 additions & 1 deletion
docs/source/cpp/compute.rst

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1545,7 +1545,7 @@ is the same, even though the UTC years would be different.
Timezone handling
~~~~~~~~~~~~~~~~~

This function is meant to be used when an external system produces
`assume_timezone` function is meant to be used when an external system produces
"timezone-naive" timestamps which need to be converted to "timezone-aware"
timestamps (see for example the `definition
<https://docs.python.org/3/library/datetime.html#aware-and-naive-objects>`__
Expand All@@ -1556,11 +1556,20 @@ Input timestamps are assumed to be relative to the timezone given in
UTC-relative timestamps with the timezone metadata set to the above value.
An error is returned if the timestamps already have the timezone metadata set.

`local_time` function converts UTC-relative timestamps to local "timezone-naive"
timestamps. The timezone is taken from the timezone metadata of the input
timestamps. This function is the inverse of `assume_timezone`. Please note:
**all temporal functions already operate on timestamps as if they were in local
time of the metadata provided timezone**. Using `local_time` is only meant to be
used when an external system expects local timestamps.

+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| Function name | Arity | Input types | Output type | Options class | Notes |
+====================+============+===================+===============+==================================+=======+
| assume_timezone | Unary | Timestamp | Timestamp | :struct:`AssumeTimezoneOptions` | \(1) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| local_time | Unary | Timestamp | Timestamp | | \(2) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+

* \(1) In addition to the timezone value, :struct:`AssumeTimezoneOptions`
 allows choosing the behaviour when a timestamp is ambiguous or nonexistent
Expand Down

1 change: 1 addition & 0 deletions
python/pyarrow/tests/test_compute.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1951,6 +1951,7 @@ def _check_datetime_components(timestamps, timezone=None):
 assert pc.microsecond(tsa).equals(pa.array(ts.dt.microsecond % 10 ** 3))
 assert pc.nanosecond(tsa).equals(pa.array(ts.dt.nanosecond))
 assert pc.subsecond(tsa).equals(pa.array(subseconds))
 assert pc.local_time(tsa).equals(pa.array(ts.dt.tz_localize(None)))

 if ts.dt.tz:
 if ts.dt.tz is datetime.timezone.utc:
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
GH-33143: [C++] Kernel to convert timestamp with timezone to wall time#34208

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 Merged

westonpace
merged 4 commits into

from

Feb 17, 2023
 Merged


GH-33143: [C++] Kernel to convert timestamp with timezone to wall time
#34208
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8857c38

Adding local_time kernel


rok Feb 15, 2023
a5185a2

More test cases. Python tests.


rok Feb 16, 2023
115347e

Review feedback


rok Feb 17, 2023
cf2eb81

Apply suggestions from code review


rok Feb 17, 2023

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1 change: 1 addition & 0 deletions
cpp/src/arrow/compute/api_scalar.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -834,6 +834,7 @@ SCALAR_EAGER_UNARY(DayOfYear, "day_of_year")
SCALAR_EAGER_UNARY(Hour, "hour")
SCALAR_EAGER_UNARY(YearMonthDay, "year_month_day")
SCALAR_EAGER_UNARY(IsDaylightSavings, "is_dst")
SCALAR_EAGER_UNARY(LocalTime, "local_time")
SCALAR_EAGER_UNARY(IsLeapYear, "is_leap_year")
SCALAR_EAGER_UNARY(ISOCalendar, "iso_calendar")
SCALAR_EAGER_UNARY(ISOWeek, "iso_week")
Expand Down

10 changes: 10 additions & 0 deletions
cpp/src/arrow/compute/api_scalar.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1518,6 +1518,16 @@ ARROW_EXPORT Result<Datum> AssumeTimezone(const Datum& values,
ARROW_EXPORT Result<Datum> IsDaylightSavings(const Datum& values,
 ExecContext* ctx = NULLPTR);

/// \brief LocalTime converts timestamp to timezone naive local timestamp
///
/// \param[in] values input to convert to local time
/// \param[in] ctx the function execution context, optional
/// \return the resulting datum
///
/// \since 12.0.0
/// \note API not yet finalized
@westonpacewestonpaceFeb 17, 2023

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I was going to suggest removing this but now I see this is everywhere. Hmm.... :( I'm not sure how true this is these days.
@rokrokFeb 17, 2023

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Well, you could see it as an opportunity to sync the API with substrait :D
ARROW_EXPORT Result<Datum> LocalTime(const Datum& values, ExecContext* ctx = NULLPTR);

/// \brief Years Between finds the number of years between two values
///
/// \param[in] left input treated as the start time
Expand Down

33 changes: 33 additions & 0 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_test.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1811,6 +1811,39 @@ TEST_F(ScalarTemporalTest, TestTemporalDifferenceErrors) {
 CallFunction("weeks_between", {arr1, arr1}, &options));
}

TEST_F(ScalarTemporalTest, TestLocalTime) {
 const char* times_seconds_precision =
 R"(["1970-01-01T00:00:59", "2000-02-29T23:23:23", "2033-05-18T03:33:20",
 "2020-01-01T01:05:05", "2019-12-31T02:10:10", "2019-12-30T03:15:15",
 "2009-12-31T04:20:20", "2010-01-01T05:25:25", "2010-01-03T06:30:30",
 "2010-01-04T07:35:35", "2006-01-01T08:40:40", "2005-12-31T09:45:45",
 "2008-12-28", "2008-12-29", "2012-01-01 01:02:03", null])";

 const char* expected_local_kolkata =
 R"(["1970-01-01 05:30:59", "2000-03-01 04:53:23", "2033-05-18 09:03:20",
 "2020-01-01 06:35:05", "2019-12-31 07:40:10", "2019-12-30 08:45:15",
 "2009-12-31 09:50:20", "2010-01-01 10:55:25", "2010-01-03 12:00:30",
 "2010-01-04 13:05:35", "2006-01-01 14:10:40", "2005-12-31 15:15:45",
 "2008-12-28 05:30:00", "2008-12-29 05:30:00", "2012-01-01 06:32:03", null])";
 const char* expected_local_marquesas =
 R"(["1969-12-31 14:30:59", "2000-02-29 13:53:23", "2033-05-17 18:03:20",
 "2019-12-31 15:35:05", "2019-12-30 16:40:10", "2019-12-29 17:45:15",
 "2009-12-30 18:50:20", "2009-12-31 19:55:25", "2010-01-02 21:00:30",
 "2010-01-03 22:05:35", "2005-12-31 23:10:40", "2005-12-31 00:15:45",
 "2008-12-27 14:30:00", "2008-12-28 14:30:00", "2011-12-31 15:32:03", null])";

 for (auto u : TimeUnit::values()) {
 CheckScalarUnary("local_time", timestamp(u), times_seconds_precision, timestamp(u),
 times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "UTC"), times_seconds_precision,
 timestamp(u), times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "Asia/Kolkata"), times_seconds_precision,
 timestamp(u), expected_local_kolkata);
 CheckScalarUnary("local_time", timestamp(u, "Pacific/Marquesas"),
 times_seconds_precision, timestamp(u), expected_local_marquesas);
 }
}

TEST_F(ScalarTemporalTest, TestAssumeTimezone) {
 std::string timezone_utc = "UTC";
 std::string timezone_kolkata = "Asia/Kolkata";
Expand Down

41 changes: 39 additions & 2 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_unary.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -672,6 +672,23 @@ struct IsDaylightSavings {
 const time_zone* tz_;
};

// ----------------------------------------------------------------------
// Extract local time of a given timestamp given its timezone

template <typename Duration, typename Localizer>
struct LocalTime {
 explicit LocalTime(const FunctionOptions* options, Localizer&& localizer)
 : localizer_(std::move(localizer)) {}

 template <typename T, typename Arg0>
 T Call(KernelContext*, Arg0 arg, Status*) const {
 const auto t = localizer_.template ConvertTimePoint<Duration>(arg);
 return static_cast<T>(t.time_since_epoch().count());
 }

 Localizer localizer_;
};

// ----------------------------------------------------------------------
// Round temporal values to given frequency

Expand DownExpand Up@@ -1327,6 +1344,12 @@ Result<TypeHolder> ResolveAssumeTimezoneOutput(KernelContext* ctx,
 return timestamp(in_type.unit(), AssumeTimezoneState::Get(ctx).timezone);
}

Result<TypeHolder> ResolveLocalTimeOutput(KernelContext* ctx,
 const std::vector<TypeHolder>& args) {
 const auto& in_type = checked_cast<const TimestampType&>(*args[0]);
 return timestamp(in_type.unit());
}

template <typename Duration>
struct AssumeTimezone {
 explicit AssumeTimezone(const AssumeTimezoneOptions* options, const time_zone* tz)
Expand DownExpand Up@@ -1784,6 +1807,13 @@ const FunctionDoc is_dst_doc{
 "An error is returned if the values do not have a defined timezone."),
 {"values"}};

const FunctionDoc local_time_doc{
 "Convert timestamp to a timezone-naive local time timestamp",
 ("LocalTime converts a timestamp to a local time of timestamps timezone\n"
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Something is missing in this sentence?
 "and removes timezone metadata. If input is in UTC or doesn't have\n"
 "timezone metadata, it is returned as is.\n"

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+1813
 to 
+1814

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Returned "as is" is not entirely correct for UTC, as I assume the "UTC" timezone is still removed?
 "Null values emit null."),
 {"values"}};
const FunctionDoc floor_temporal_doc{
 "Round temporal values down to nearest multiple of specified time unit",
 ("Null values emit null.\n"
Expand All@@ -1801,8 +1831,9 @@ const FunctionDoc ceil_temporal_doc{
const FunctionDoc round_temporal_doc{
 "Round temporal values to the nearest multiple of specified time unit",
 ("Null values emit null.\n"
 "An error is returned if the values have a defined timezone but it\n"
 "cannot be found in the timezone database."),
 "If timezone is not given then timezone naive timestamp in UTC are\n"
 "returned. An error is returned if the values have a defined timezone\n"
 "but it cannot be found in the timezone database."),
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Was this change intentional? Or was it meant to be in local_time_doc?

(and if intentional, why only for round and not ceil/floor?)
 {"timestamps"},
 "RoundTemporalOptions"};

Expand DownExpand Up@@ -1969,6 +2000,12 @@ void RegisterScalarTemporalUnary(FunctionRegistry* registry) {
 is_dst_doc);
 DCHECK_OK(registry->AddFunction(std::move(is_dst)));

 auto local_time =
 UnaryTemporalFactory<LocalTime, TemporalComponentExtract, TimestampType>::Make<
 WithTimestamps>("local_time", OutputType::Resolver(ResolveLocalTimeOutput),
 local_time_doc);
 DCHECK_OK(registry->AddFunction(std::move(local_time)));

 // Temporal rounding functions
 // Note: UnaryTemporalFactory will not correctly resolve OutputType(FirstType) to
 // output type. See TemporalComponentExtractRound for more.
Expand Down

11 changes: 10 additions & 1 deletion
docs/source/cpp/compute.rst

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1545,7 +1545,7 @@ is the same, even though the UTC years would be different.
Timezone handling
~~~~~~~~~~~~~~~~~

This function is meant to be used when an external system produces
`assume_timezone` function is meant to be used when an external system produces
"timezone-naive" timestamps which need to be converted to "timezone-aware"
timestamps (see for example the `definition
<https://docs.python.org/3/library/datetime.html#aware-and-naive-objects>`__
Expand All@@ -1556,11 +1556,20 @@ Input timestamps are assumed to be relative to the timezone given in
UTC-relative timestamps with the timezone metadata set to the above value.
An error is returned if the timestamps already have the timezone metadata set.

`local_time` function converts UTC-relative timestamps to local "timezone-naive"
timestamps. The timezone is taken from the timezone metadata of the input
timestamps. This function is the inverse of `assume_timezone`. Please note:
**all temporal functions already operate on timestamps as if they were in local
time of the metadata provided timezone**. Using `local_time` is only meant to be
used when an external system expects local timestamps.

+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| Function name | Arity | Input types | Output type | Options class | Notes |
+====================+============+===================+===============+==================================+=======+
| assume_timezone | Unary | Timestamp | Timestamp | :struct:`AssumeTimezoneOptions` | \(1) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| local_time | Unary | Timestamp | Timestamp | | \(2) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+

* \(1) In addition to the timezone value, :struct:`AssumeTimezoneOptions`
 allows choosing the behaviour when a timestamp is ambiguous or nonexistent
Expand Down

1 change: 1 addition & 0 deletions
python/pyarrow/tests/test_compute.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1951,6 +1951,7 @@ def _check_datetime_components(timestamps, timezone=None):
 assert pc.microsecond(tsa).equals(pa.array(ts.dt.microsecond % 10 ** 3))
 assert pc.nanosecond(tsa).equals(pa.array(ts.dt.nanosecond))
 assert pc.subsecond(tsa).equals(pa.array(subseconds))
 assert pc.local_time(tsa).equals(pa.array(ts.dt.tz_localize(None)))

 if ts.dt.tz:
 if ts.dt.tz is datetime.timezone.utc:
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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GH-33143: [C++] Kernel to convert timestamp with timezone to wall time#34208

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 Merged

westonpace
merged 4 commits into

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Feb 17, 2023
 Merged


GH-33143: [C++] Kernel to convert timestamp with timezone to wall time
#34208
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8857c38

Adding local_time kernel


rok Feb 15, 2023
a5185a2

More test cases. Python tests.


rok Feb 16, 2023
115347e

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rok Feb 17, 2023
cf2eb81

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rok Feb 17, 2023

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1 change: 1 addition & 0 deletions
cpp/src/arrow/compute/api_scalar.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -834,6 +834,7 @@ SCALAR_EAGER_UNARY(DayOfYear, "day_of_year")
SCALAR_EAGER_UNARY(Hour, "hour")
SCALAR_EAGER_UNARY(YearMonthDay, "year_month_day")
SCALAR_EAGER_UNARY(IsDaylightSavings, "is_dst")
SCALAR_EAGER_UNARY(LocalTime, "local_time")
SCALAR_EAGER_UNARY(IsLeapYear, "is_leap_year")
SCALAR_EAGER_UNARY(ISOCalendar, "iso_calendar")
SCALAR_EAGER_UNARY(ISOWeek, "iso_week")
Expand Down

10 changes: 10 additions & 0 deletions
cpp/src/arrow/compute/api_scalar.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1518,6 +1518,16 @@ ARROW_EXPORT Result<Datum> AssumeTimezone(const Datum& values,
ARROW_EXPORT Result<Datum> IsDaylightSavings(const Datum& values,
 ExecContext* ctx = NULLPTR);

/// \brief LocalTime converts timestamp to timezone naive local timestamp
///
/// \param[in] values input to convert to local time
/// \param[in] ctx the function execution context, optional
/// \return the resulting datum
///
/// \since 12.0.0
/// \note API not yet finalized
@westonpacewestonpaceFeb 17, 2023

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I was going to suggest removing this but now I see this is everywhere. Hmm.... :( I'm not sure how true this is these days.
@rokrokFeb 17, 2023

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Well, you could see it as an opportunity to sync the API with substrait :D
ARROW_EXPORT Result<Datum> LocalTime(const Datum& values, ExecContext* ctx = NULLPTR);

/// \brief Years Between finds the number of years between two values
///
/// \param[in] left input treated as the start time
Expand Down

33 changes: 33 additions & 0 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_test.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1811,6 +1811,39 @@ TEST_F(ScalarTemporalTest, TestTemporalDifferenceErrors) {
 CallFunction("weeks_between", {arr1, arr1}, &options));
}

TEST_F(ScalarTemporalTest, TestLocalTime) {
 const char* times_seconds_precision =
 R"(["1970-01-01T00:00:59", "2000-02-29T23:23:23", "2033-05-18T03:33:20",
 "2020-01-01T01:05:05", "2019-12-31T02:10:10", "2019-12-30T03:15:15",
 "2009-12-31T04:20:20", "2010-01-01T05:25:25", "2010-01-03T06:30:30",
 "2010-01-04T07:35:35", "2006-01-01T08:40:40", "2005-12-31T09:45:45",
 "2008-12-28", "2008-12-29", "2012-01-01 01:02:03", null])";

 const char* expected_local_kolkata =
 R"(["1970-01-01 05:30:59", "2000-03-01 04:53:23", "2033-05-18 09:03:20",
 "2020-01-01 06:35:05", "2019-12-31 07:40:10", "2019-12-30 08:45:15",
 "2009-12-31 09:50:20", "2010-01-01 10:55:25", "2010-01-03 12:00:30",
 "2010-01-04 13:05:35", "2006-01-01 14:10:40", "2005-12-31 15:15:45",
 "2008-12-28 05:30:00", "2008-12-29 05:30:00", "2012-01-01 06:32:03", null])";
 const char* expected_local_marquesas =
 R"(["1969-12-31 14:30:59", "2000-02-29 13:53:23", "2033-05-17 18:03:20",
 "2019-12-31 15:35:05", "2019-12-30 16:40:10", "2019-12-29 17:45:15",
 "2009-12-30 18:50:20", "2009-12-31 19:55:25", "2010-01-02 21:00:30",
 "2010-01-03 22:05:35", "2005-12-31 23:10:40", "2005-12-31 00:15:45",
 "2008-12-27 14:30:00", "2008-12-28 14:30:00", "2011-12-31 15:32:03", null])";

 for (auto u : TimeUnit::values()) {
 CheckScalarUnary("local_time", timestamp(u), times_seconds_precision, timestamp(u),
 times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "UTC"), times_seconds_precision,
 timestamp(u), times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "Asia/Kolkata"), times_seconds_precision,
 timestamp(u), expected_local_kolkata);
 CheckScalarUnary("local_time", timestamp(u, "Pacific/Marquesas"),
 times_seconds_precision, timestamp(u), expected_local_marquesas);
 }
}

TEST_F(ScalarTemporalTest, TestAssumeTimezone) {
 std::string timezone_utc = "UTC";
 std::string timezone_kolkata = "Asia/Kolkata";
Expand Down

41 changes: 39 additions & 2 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_unary.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -672,6 +672,23 @@ struct IsDaylightSavings {
 const time_zone* tz_;
};

// ----------------------------------------------------------------------
// Extract local time of a given timestamp given its timezone

template <typename Duration, typename Localizer>
struct LocalTime {
 explicit LocalTime(const FunctionOptions* options, Localizer&& localizer)
 : localizer_(std::move(localizer)) {}

 template <typename T, typename Arg0>
 T Call(KernelContext*, Arg0 arg, Status*) const {
 const auto t = localizer_.template ConvertTimePoint<Duration>(arg);
 return static_cast<T>(t.time_since_epoch().count());
 }

 Localizer localizer_;
};

// ----------------------------------------------------------------------
// Round temporal values to given frequency

Expand DownExpand Up@@ -1327,6 +1344,12 @@ Result<TypeHolder> ResolveAssumeTimezoneOutput(KernelContext* ctx,
 return timestamp(in_type.unit(), AssumeTimezoneState::Get(ctx).timezone);
}

Result<TypeHolder> ResolveLocalTimeOutput(KernelContext* ctx,
 const std::vector<TypeHolder>& args) {
 const auto& in_type = checked_cast<const TimestampType&>(*args[0]);
 return timestamp(in_type.unit());
}

template <typename Duration>
struct AssumeTimezone {
 explicit AssumeTimezone(const AssumeTimezoneOptions* options, const time_zone* tz)
Expand DownExpand Up@@ -1784,6 +1807,13 @@ const FunctionDoc is_dst_doc{
 "An error is returned if the values do not have a defined timezone."),
 {"values"}};

const FunctionDoc local_time_doc{
 "Convert timestamp to a timezone-naive local time timestamp",
 ("LocalTime converts a timestamp to a local time of timestamps timezone\n"
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Something is missing in this sentence?
 "and removes timezone metadata. If input is in UTC or doesn't have\n"
 "timezone metadata, it is returned as is.\n"

Comment on lines

+1813
 to 
+1814

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Returned "as is" is not entirely correct for UTC, as I assume the "UTC" timezone is still removed?
 "Null values emit null."),
 {"values"}};
const FunctionDoc floor_temporal_doc{
 "Round temporal values down to nearest multiple of specified time unit",
 ("Null values emit null.\n"
Expand All@@ -1801,8 +1831,9 @@ const FunctionDoc ceil_temporal_doc{
const FunctionDoc round_temporal_doc{
 "Round temporal values to the nearest multiple of specified time unit",
 ("Null values emit null.\n"
 "An error is returned if the values have a defined timezone but it\n"
 "cannot be found in the timezone database."),
 "If timezone is not given then timezone naive timestamp in UTC are\n"
 "returned. An error is returned if the values have a defined timezone\n"
 "but it cannot be found in the timezone database."),
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Was this change intentional? Or was it meant to be in local_time_doc?

(and if intentional, why only for round and not ceil/floor?)
 {"timestamps"},
 "RoundTemporalOptions"};

Expand DownExpand Up@@ -1969,6 +2000,12 @@ void RegisterScalarTemporalUnary(FunctionRegistry* registry) {
 is_dst_doc);
 DCHECK_OK(registry->AddFunction(std::move(is_dst)));

 auto local_time =
 UnaryTemporalFactory<LocalTime, TemporalComponentExtract, TimestampType>::Make<
 WithTimestamps>("local_time", OutputType::Resolver(ResolveLocalTimeOutput),
 local_time_doc);
 DCHECK_OK(registry->AddFunction(std::move(local_time)));

 // Temporal rounding functions
 // Note: UnaryTemporalFactory will not correctly resolve OutputType(FirstType) to
 // output type. See TemporalComponentExtractRound for more.
Expand Down

11 changes: 10 additions & 1 deletion
docs/source/cpp/compute.rst

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1545,7 +1545,7 @@ is the same, even though the UTC years would be different.
Timezone handling
~~~~~~~~~~~~~~~~~

This function is meant to be used when an external system produces
`assume_timezone` function is meant to be used when an external system produces
"timezone-naive" timestamps which need to be converted to "timezone-aware"
timestamps (see for example the `definition
<https://docs.python.org/3/library/datetime.html#aware-and-naive-objects>`__
Expand All@@ -1556,11 +1556,20 @@ Input timestamps are assumed to be relative to the timezone given in
UTC-relative timestamps with the timezone metadata set to the above value.
An error is returned if the timestamps already have the timezone metadata set.

`local_time` function converts UTC-relative timestamps to local "timezone-naive"
timestamps. The timezone is taken from the timezone metadata of the input
timestamps. This function is the inverse of `assume_timezone`. Please note:
**all temporal functions already operate on timestamps as if they were in local
time of the metadata provided timezone**. Using `local_time` is only meant to be
used when an external system expects local timestamps.

+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| Function name | Arity | Input types | Output type | Options class | Notes |
+====================+============+===================+===============+==================================+=======+
| assume_timezone | Unary | Timestamp | Timestamp | :struct:`AssumeTimezoneOptions` | \(1) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| local_time | Unary | Timestamp | Timestamp | | \(2) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+

* \(1) In addition to the timezone value, :struct:`AssumeTimezoneOptions`
 allows choosing the behaviour when a timestamp is ambiguous or nonexistent
Expand Down

1 change: 1 addition & 0 deletions
python/pyarrow/tests/test_compute.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1951,6 +1951,7 @@ def _check_datetime_components(timestamps, timezone=None):
 assert pc.microsecond(tsa).equals(pa.array(ts.dt.microsecond % 10 ** 3))
 assert pc.nanosecond(tsa).equals(pa.array(ts.dt.nanosecond))
 assert pc.subsecond(tsa).equals(pa.array(subseconds))
 assert pc.local_time(tsa).equals(pa.array(ts.dt.tz_localize(None)))

 if ts.dt.tz:
 if ts.dt.tz is datetime.timezone.utc:
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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GH-33143: [C++] Kernel to convert timestamp with timezone to wall time#34208

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 Merged

westonpace
merged 4 commits into

from

Feb 17, 2023
 Merged


GH-33143: [C++] Kernel to convert timestamp with timezone to wall time
#34208
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8857c38

Adding local_time kernel


rok Feb 15, 2023
a5185a2

More test cases. Python tests.


rok Feb 16, 2023
115347e

Review feedback


rok Feb 17, 2023
cf2eb81

Apply suggestions from code review


rok Feb 17, 2023

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1 change: 1 addition & 0 deletions
cpp/src/arrow/compute/api_scalar.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -834,6 +834,7 @@ SCALAR_EAGER_UNARY(DayOfYear, "day_of_year")
SCALAR_EAGER_UNARY(Hour, "hour")
SCALAR_EAGER_UNARY(YearMonthDay, "year_month_day")
SCALAR_EAGER_UNARY(IsDaylightSavings, "is_dst")
SCALAR_EAGER_UNARY(LocalTime, "local_time")
SCALAR_EAGER_UNARY(IsLeapYear, "is_leap_year")
SCALAR_EAGER_UNARY(ISOCalendar, "iso_calendar")
SCALAR_EAGER_UNARY(ISOWeek, "iso_week")
Expand Down

10 changes: 10 additions & 0 deletions
cpp/src/arrow/compute/api_scalar.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1518,6 +1518,16 @@ ARROW_EXPORT Result<Datum> AssumeTimezone(const Datum& values,
ARROW_EXPORT Result<Datum> IsDaylightSavings(const Datum& values,
 ExecContext* ctx = NULLPTR);

/// \brief LocalTime converts timestamp to timezone naive local timestamp
///
/// \param[in] values input to convert to local time
/// \param[in] ctx the function execution context, optional
/// \return the resulting datum
///
/// \since 12.0.0
/// \note API not yet finalized
@westonpacewestonpaceFeb 17, 2023

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I was going to suggest removing this but now I see this is everywhere. Hmm.... :( I'm not sure how true this is these days.
@rokrokFeb 17, 2023

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Well, you could see it as an opportunity to sync the API with substrait :D
ARROW_EXPORT Result<Datum> LocalTime(const Datum& values, ExecContext* ctx = NULLPTR);

/// \brief Years Between finds the number of years between two values
///
/// \param[in] left input treated as the start time
Expand Down

33 changes: 33 additions & 0 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_test.cc

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1811,6 +1811,39 @@ TEST_F(ScalarTemporalTest, TestTemporalDifferenceErrors) {
 CallFunction("weeks_between", {arr1, arr1}, &options));
}

TEST_F(ScalarTemporalTest, TestLocalTime) {
 const char* times_seconds_precision =
 R"(["1970-01-01T00:00:59", "2000-02-29T23:23:23", "2033-05-18T03:33:20",
 "2020-01-01T01:05:05", "2019-12-31T02:10:10", "2019-12-30T03:15:15",
 "2009-12-31T04:20:20", "2010-01-01T05:25:25", "2010-01-03T06:30:30",
 "2010-01-04T07:35:35", "2006-01-01T08:40:40", "2005-12-31T09:45:45",
 "2008-12-28", "2008-12-29", "2012-01-01 01:02:03", null])";

 const char* expected_local_kolkata =
 R"(["1970-01-01 05:30:59", "2000-03-01 04:53:23", "2033-05-18 09:03:20",
 "2020-01-01 06:35:05", "2019-12-31 07:40:10", "2019-12-30 08:45:15",
 "2009-12-31 09:50:20", "2010-01-01 10:55:25", "2010-01-03 12:00:30",
 "2010-01-04 13:05:35", "2006-01-01 14:10:40", "2005-12-31 15:15:45",
 "2008-12-28 05:30:00", "2008-12-29 05:30:00", "2012-01-01 06:32:03", null])";
 const char* expected_local_marquesas =
 R"(["1969-12-31 14:30:59", "2000-02-29 13:53:23", "2033-05-17 18:03:20",
 "2019-12-31 15:35:05", "2019-12-30 16:40:10", "2019-12-29 17:45:15",
 "2009-12-30 18:50:20", "2009-12-31 19:55:25", "2010-01-02 21:00:30",
 "2010-01-03 22:05:35", "2005-12-31 23:10:40", "2005-12-31 00:15:45",
 "2008-12-27 14:30:00", "2008-12-28 14:30:00", "2011-12-31 15:32:03", null])";

 for (auto u : TimeUnit::values()) {
 CheckScalarUnary("local_time", timestamp(u), times_seconds_precision, timestamp(u),
 times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "UTC"), times_seconds_precision,
 timestamp(u), times_seconds_precision);
 CheckScalarUnary("local_time", timestamp(u, "Asia/Kolkata"), times_seconds_precision,
 timestamp(u), expected_local_kolkata);
 CheckScalarUnary("local_time", timestamp(u, "Pacific/Marquesas"),
 times_seconds_precision, timestamp(u), expected_local_marquesas);
 }
}

TEST_F(ScalarTemporalTest, TestAssumeTimezone) {
 std::string timezone_utc = "UTC";
 std::string timezone_kolkata = "Asia/Kolkata";
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41 changes: 39 additions & 2 deletions
cpp/src/arrow/compute/kernels/scalar_temporal_unary.cc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -672,6 +672,23 @@ struct IsDaylightSavings {
 const time_zone* tz_;
};

// ----------------------------------------------------------------------
// Extract local time of a given timestamp given its timezone

template <typename Duration, typename Localizer>
struct LocalTime {
 explicit LocalTime(const FunctionOptions* options, Localizer&& localizer)
 : localizer_(std::move(localizer)) {}

 template <typename T, typename Arg0>
 T Call(KernelContext*, Arg0 arg, Status*) const {
 const auto t = localizer_.template ConvertTimePoint<Duration>(arg);
 return static_cast<T>(t.time_since_epoch().count());
 }

 Localizer localizer_;
};

// ----------------------------------------------------------------------
// Round temporal values to given frequency

Expand DownExpand Up@@ -1327,6 +1344,12 @@ Result<TypeHolder> ResolveAssumeTimezoneOutput(KernelContext* ctx,
 return timestamp(in_type.unit(), AssumeTimezoneState::Get(ctx).timezone);
}

Result<TypeHolder> ResolveLocalTimeOutput(KernelContext* ctx,
 const std::vector<TypeHolder>& args) {
 const auto& in_type = checked_cast<const TimestampType&>(*args[0]);
 return timestamp(in_type.unit());
}

template <typename Duration>
struct AssumeTimezone {
 explicit AssumeTimezone(const AssumeTimezoneOptions* options, const time_zone* tz)
Expand DownExpand Up@@ -1784,6 +1807,13 @@ const FunctionDoc is_dst_doc{
 "An error is returned if the values do not have a defined timezone."),
 {"values"}};

const FunctionDoc local_time_doc{
 "Convert timestamp to a timezone-naive local time timestamp",
 ("LocalTime converts a timestamp to a local time of timestamps timezone\n"
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Something is missing in this sentence?
 "and removes timezone metadata. If input is in UTC or doesn't have\n"
 "timezone metadata, it is returned as is.\n"

Comment on lines

+1813
 to 
+1814

@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Returned "as is" is not entirely correct for UTC, as I assume the "UTC" timezone is still removed?
 "Null values emit null."),
 {"values"}};
const FunctionDoc floor_temporal_doc{
 "Round temporal values down to nearest multiple of specified time unit",
 ("Null values emit null.\n"
Expand All@@ -1801,8 +1831,9 @@ const FunctionDoc ceil_temporal_doc{
const FunctionDoc round_temporal_doc{
 "Round temporal values to the nearest multiple of specified time unit",
 ("Null values emit null.\n"
 "An error is returned if the values have a defined timezone but it\n"
 "cannot be found in the timezone database."),
 "If timezone is not given then timezone naive timestamp in UTC are\n"
 "returned. An error is returned if the values have a defined timezone\n"
 "but it cannot be found in the timezone database."),
@jorisvandenbosschejorisvandenbosscheFeb 20, 2023

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Was this change intentional? Or was it meant to be in local_time_doc?

(and if intentional, why only for round and not ceil/floor?)
 {"timestamps"},
 "RoundTemporalOptions"};

Expand DownExpand Up@@ -1969,6 +2000,12 @@ void RegisterScalarTemporalUnary(FunctionRegistry* registry) {
 is_dst_doc);
 DCHECK_OK(registry->AddFunction(std::move(is_dst)));

 auto local_time =
 UnaryTemporalFactory<LocalTime, TemporalComponentExtract, TimestampType>::Make<
 WithTimestamps>("local_time", OutputType::Resolver(ResolveLocalTimeOutput),
 local_time_doc);
 DCHECK_OK(registry->AddFunction(std::move(local_time)));

 // Temporal rounding functions
 // Note: UnaryTemporalFactory will not correctly resolve OutputType(FirstType) to
 // output type. See TemporalComponentExtractRound for more.
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11 changes: 10 additions & 1 deletion
docs/source/cpp/compute.rst

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1545,7 +1545,7 @@ is the same, even though the UTC years would be different.
Timezone handling
~~~~~~~~~~~~~~~~~

This function is meant to be used when an external system produces
`assume_timezone` function is meant to be used when an external system produces
"timezone-naive" timestamps which need to be converted to "timezone-aware"
timestamps (see for example the `definition
<https://docs.python.org/3/library/datetime.html#aware-and-naive-objects>`__
Expand All@@ -1556,11 +1556,20 @@ Input timestamps are assumed to be relative to the timezone given in
UTC-relative timestamps with the timezone metadata set to the above value.
An error is returned if the timestamps already have the timezone metadata set.

`local_time` function converts UTC-relative timestamps to local "timezone-naive"
timestamps. The timezone is taken from the timezone metadata of the input
timestamps. This function is the inverse of `assume_timezone`. Please note:
**all temporal functions already operate on timestamps as if they were in local
time of the metadata provided timezone**. Using `local_time` is only meant to be
used when an external system expects local timestamps.

+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| Function name | Arity | Input types | Output type | Options class | Notes |
+====================+============+===================+===============+==================================+=======+
| assume_timezone | Unary | Timestamp | Timestamp | :struct:`AssumeTimezoneOptions` | \(1) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+
| local_time | Unary | Timestamp | Timestamp | | \(2) |
+--------------------+------------+-------------------+---------------+----------------------------------+-------+

* \(1) In addition to the timezone value, :struct:`AssumeTimezoneOptions`
 allows choosing the behaviour when a timestamp is ambiguous or nonexistent
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1 change: 1 addition & 0 deletions
python/pyarrow/tests/test_compute.py

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1951,6 +1951,7 @@ def _check_datetime_components(timestamps, timezone=None):
 assert pc.microsecond(tsa).equals(pa.array(ts.dt.microsecond % 10 ** 3))
 assert pc.nanosecond(tsa).equals(pa.array(ts.dt.nanosecond))
 assert pc.subsecond(tsa).equals(pa.array(subseconds))
 assert pc.local_time(tsa).equals(pa.array(ts.dt.tz_localize(None)))

 if ts.dt.tz:
 if ts.dt.tz is datetime.timezone.utc:
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