cpython/Lib/bisect.py at main · python/cpython · GitHub

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"""Bisection algorithms."""


definsort_right(a, x, lo=0, hi=None, *, key=None):
"""Insert item x in list a, and keep it sorted assuming a is sorted.

 If x is already in a, insert it to the right of the rightmost x.

 Optional args lo (default 0) and hi (default len(a)) bound the
 slice of a to be searched.

 A custom key function can be supplied to customize the sort order.
 """
ifkeyisNone:
lo=bisect_right(a, x, lo, hi)
else:
lo=bisect_right(a, key(x), lo, hi, key=key)
a.insert(lo, x)


defbisect_right(a, x, lo=0, hi=None, *, key=None):
"""Return the index where to insert item x in list a, assuming a is sorted.

 The return value i is such that all e in a[:i] have e <= x, and all e in
 a[i:] have e > x. So if x already appears in the list, a.insert(i, x) will
 insert just after the rightmost x already there.

 Optional args lo (default 0) and hi (default len(a)) bound the
 slice of a to be searched.

 A custom key function can be supplied to customize the sort order.
 """

iflo<0:
raiseValueError('lo must be non-negative')
ifhiisNone:
hi=len(a)
# Note, the comparison uses "<" to match the
# __lt__() logic in list.sort() and in heapq.
ifkeyisNone:
whilelo<hi:
mid= (lo+hi) //2
ifx<a[mid]:
hi=mid
else:
lo=mid+1
else:
whilelo<hi:
mid= (lo+hi) //2
ifx<key(a[mid]):
hi=mid
else:
lo=mid+1
returnlo


definsort_left(a, x, lo=0, hi=None, *, key=None):
"""Insert item x in list a, and keep it sorted assuming a is sorted.

 If x is already in a, insert it to the left of the leftmost x.

 Optional args lo (default 0) and hi (default len(a)) bound the
 slice of a to be searched.

 A custom key function can be supplied to customize the sort order.
 """

ifkeyisNone:
lo=bisect_left(a, x, lo, hi)
else:
lo=bisect_left(a, key(x), lo, hi, key=key)
a.insert(lo, x)

defbisect_left(a, x, lo=0, hi=None, *, key=None):
"""Return the index where to insert item x in list a, assuming a is sorted.

 The return value i is such that all e in a[:i] have e < x, and all e in
 a[i:] have e >= x. So if x already appears in the list, a.insert(i, x) will
 insert just before the leftmost x already there.

 Optional args lo (default 0) and hi (default len(a)) bound the
 slice of a to be searched.

 A custom key function can be supplied to customize the sort order.
 """

iflo<0:
raiseValueError('lo must be non-negative')
ifhiisNone:
hi=len(a)
# Note, the comparison uses "<" to match the
# __lt__() logic in list.sort() and in heapq.
ifkeyisNone:
whilelo<hi:
mid= (lo+hi) //2
ifa[mid] <x:
lo=mid+1
else:
hi=mid
else:
whilelo<hi:
mid= (lo+hi) //2
ifkey(a[mid]) <x:
lo=mid+1
else:
hi=mid
returnlo


# Overwrite above definitions with a fast C implementation
try:
from_bisectimport*
exceptImportError:
pass

# Create aliases
bisect=bisect_right
insort=insort_right