pygmt.conf() can't find default for FONT

[liamtoney]

Description of the problem

The code

with pygmt.clib.Session() as session:
 session.call_module('gmtset', 'FONT 8p')

runs fine. But the equivalent pygmt.config() has trouble.

Full code that generated the error

pygmt.config(FONT='8p')

Full error message

pygmt-session [ERROR]: Syntax error: Unrecognized keyword FONT
Traceback (most recent call last):
 File "/opt/miniconda3/envs/liam/lib/python3.7/site-packages/IPython/core/interactiveshell.py", line 3326, in run_code
 exec(code_obj, self.user_global_ns, self.user_ns)
 File "<ipython-input-19-8e431d18430a>", line 1, in <module>
 pygmt.config(FONT='8p')
 File "/opt/miniconda3/envs/liam/lib/python3.7/site-packages/pygmt/modules.py", line 168, in __init__
 self.old_defaults[key] = lib.get_default(key)
 File "/opt/miniconda3/envs/liam/lib/python3.7/site-packages/pygmt/clib/session.py", line 458, in get_default
 name, status
pygmt.exceptions.GMTCLibError: Error getting default value for 'FONT' (error code 67).

System information

• Operating system: macOS Catalina 10.15.4
• Python installation (Anaconda, system, ETS): Miniconda
• Version of GMT: 6.0.0
• Version of Python: 3.7.3
• Version of this package: c6f154b9916eb96e0be14740ce8b8b79c49e10f2
• If using conda, paste the output of conda list below:

output of conda list

# packages in environment at /opt/miniconda3/envs/liam:
#
# Name Version Build Channel
affine 2.3.0 py_0 conda-forge
alabaster 0.7.12 py_0 conda-forge
appdirs 1.4.3 py37h28b3542_0 
appnope 0.1.0 py37_1000 conda-forge
array-processing 0.0.0 dev_0 
attrs 19.3.0 py_0 conda-forge
babel 2.8.0 py_0 conda-forge
backcall 0.1.0 py_0 conda-forge
black 19.10b0 py_0 
boost-cpp 1.70.0 h75728bb_2 conda-forge
bzip2 1.0.8 h01d97ff_1 conda-forge
ca-certificates 2020.1.1 0 
cairo 1.16.0 he1c11cd_1002 conda-forge
cartopy 0.17.0 py37h3c2a19d_1008 conda-forge
certifi 2019.11.28 py37hc8dfbb8_1 conda-forge
cffi 1.13.2 py37h33e799b_0 conda-forge
cfitsio 3.470 h84d2f63_2 conda-forge
cftime 1.0.4.2 pypi_0 pypi
chardet 3.0.4 py37_1003 conda-forge
click 7.0 py_0 conda-forge
click-plugins 1.1.1 py_0 conda-forge
cligj 0.5.0 py_0 conda-forge
colorcet 2.0.1 py_0 conda-forge
commonmark 0.9.1 py_0 conda-forge
cryptography 2.8 py37hafa8578_0 conda-forge
curl 7.65.3 h22ea746_0 conda-forge
cycler 0.10.0 py_2 conda-forge
decorator 4.4.1 py_0 conda-forge
docutils 0.16 py37_0 conda-forge
expat 2.2.5 h4a8c4bd_1004 conda-forge
fastkml 0.11 pypi_0 pypi
fontconfig 2.13.1 h6b1039f_1001 conda-forge
freetype 2.10.0 h24853df_1 conda-forge
freexl 1.0.5 h1de35cc_1002 conda-forge
future 0.18.2 py37_0 conda-forge
gdal 3.0.2 py37h97c3584_3 conda-forge
geos 3.7.2 h6de7cb9_2 conda-forge
geotiff 1.5.1 ha113b03_7 conda-forge
gettext 0.19.8.1 h46ab8bc_1002 conda-forge
ghostscript 9.22 h0a44026_1001 conda-forge
giflib 5.1.7 h01d97ff_1 conda-forge
glib 2.58.3 py37h577aef8_1002 conda-forge
hdf4 4.2.13 h84186c3_1003 conda-forge
hdf5 1.10.5 nompi_h3e39495_1104 conda-forge
icu 64.2 h6de7cb9_1 conda-forge
idna 2.8 py37_1000 conda-forge
imagesize 1.2.0 py_0 conda-forge
ipython 7.9.0 py37h5ca1d4c_0 conda-forge
ipython_genutils 0.2.0 py_1 conda-forge
jedi 0.15.1 py37_0 conda-forge
jinja2 2.11.1 py_0 conda-forge
joblib 0.14.0 pypi_0 pypi
jpeg 9c h1de35cc_1001 conda-forge
json-c 0.13.1 h1de35cc_1001 conda-forge
kealib 1.4.10 h6659575_1005 conda-forge
kiwisolver 1.1.0 py37ha1b3eb9_0 conda-forge
krb5 1.16.3 hcfa6398_1001 conda-forge
libblas 3.8.0 14_openblas conda-forge
libcblas 3.8.0 14_openblas conda-forge
libcurl 7.65.3 h16faf7d_0 conda-forge
libcxx 9.0.1 1 conda-forge
libdap4 3.20.4 habf5908_0 conda-forge
libedit 3.1.20170329 hcfe32e1_1001 conda-forge
libffi 3.2.1 h6de7cb9_1006 conda-forge
libgdal 3.0.2 h6a635d1_3 conda-forge
libgfortran 4.0.0 2 conda-forge
libiconv 1.15 h01d97ff_1005 conda-forge
libkml 1.3.0 hed7d534_1010 conda-forge
liblapack 3.8.0 14_openblas conda-forge
libnetcdf 4.7.1 nompi_hec86efb_102 conda-forge
libopenblas 0.3.7 h4bb4525_3 conda-forge
libpng 1.6.37 h2573ce8_0 conda-forge
libpq 11.5 h31a01ba_2 conda-forge
libspatialite 4.3.0a h7a659be_1032 conda-forge
libssh2 1.8.2 hcdc9a53_2 conda-forge
libtiff 4.1.0 ha78913b_1 conda-forge
libwebp 1.0.2 h20df551_3 conda-forge
libxml2 2.9.10 h53d96d6_0 conda-forge
libxslt 1.1.33 h320ff13_0 conda-forge
llvm-openmp 9.0.0 h40edb58_0 conda-forge
lxml 4.4.1 py37he54a443_0 conda-forge
lz4-c 1.8.3 h6de7cb9_1001 conda-forge
markupsafe 1.1.1 py37h0b31af3_0 conda-forge
matplotlib 3.2.1 0 conda-forge
matplotlib-base 3.2.1 py37hddda452_0 conda-forge
mypy_extensions 0.4.3 py37_0 
ncurses 6.1 h0a44026_1002 conda-forge
netcdf4 1.5.3 pypi_0 pypi
numpy 1.17.3 py37hde6bac1_0 conda-forge
obspy 1.2.1 py37h10e2902_1 conda-forge
olefile 0.46 py_0 conda-forge
openjpeg 2.3.1 hdc36067_1 conda-forge
openssl 1.1.1e h0b31af3_0 conda-forge
owslib 0.19.0 py_0 conda-forge
packaging 19.2 py_0 conda-forge
pandas 0.25.3 py37h4f17bb1_0 conda-forge
param 1.9.2 py_0 conda-forge
parso 0.5.1 py_0 conda-forge
pathspec 0.7.0 py_0 
patsy 0.5.1 pypi_0 pypi
pbr 5.4.4 py_0 
pcre 8.43 h4a8c4bd_0 conda-forge
pexpect 4.7.0 py37_0 conda-forge
pickleshare 0.7.5 py37_1000 conda-forge
pillow 6.2.1 py37h43b43f3_1 conda-forge
pip 19.3.1 py37_0 conda-forge
pixman 0.38.0 h01d97ff_1003 conda-forge
poppler 0.67.0 h16886b5_8 conda-forge
poppler-data 0.4.9 1 conda-forge
postgresql 11.5 h26bc10f_2 conda-forge
proj 6.2.1 h773a61f_0 conda-forge
prompt_toolkit 2.0.10 py_0 conda-forge
ptyprocess 0.6.0 py_1001 conda-forge
pycparser 2.19 py37_1 conda-forge
pyct 0.4.6 py_0 conda-forge
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pyepsg 0.4.0 py_0 conda-forge
pygeoif 0.7 pypi_0 pypi
pygments 2.4.2 py_0 conda-forge
pygmt 0+unknown pypi_0 pypi
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pyopenssl 19.0.0 py37_0 conda-forge
pyparsing 2.4.5 py_0 conda-forge
pyproj 2.4.1 py37h03a428a_1 conda-forge
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pyshp 2.1.0 py_0 conda-forge
pysocks 1.7.1 py37_0 conda-forge
python 3.7.3 h93065d6_1 conda-forge
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python_abi 3.7 1_cp37m conda-forge
pytz 2019.3 py_0 conda-forge
pyyaml 5.1.2 py37h0b31af3_0 conda-forge
rasterio 1.1.1 py37he71f6a4_0 conda-forge
readline 8.0 hcfe32e1_0 conda-forge
recommonmark 0.6.0 py_0 conda-forge
regex 2020.1.8 py37h1de35cc_0 
requests 2.22.0 py37_1 conda-forge
rioxarray 0.0.17 py_0 conda-forge
rtm 0.0.0 dev_0 
scikit-learn 0.21.3 pypi_0 pypi
scipy 1.3.2 py37h82752d6_0 conda-forge
seisk 0.1.dev0 dev_0 
setuptools 42.0.0 py37_0 conda-forge
shapely 1.6.4 py37h5c88e11_1006 conda-forge
simplekml 1.3.3 pypi_0 pypi
six 1.13.0 py37_0 conda-forge
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snuggs 1.4.7 py_0 conda-forge
sphinx 2.4.3 py_0 conda-forge
sphinx_rtd_theme 0.4.3 py_0 conda-forge
sphinxcontrib-apidoc 0.3.0 py_1 conda-forge
sphinxcontrib-applehelp 1.0.1 py_0 conda-forge
sphinxcontrib-devhelp 1.0.1 py_0 conda-forge
sphinxcontrib-htmlhelp 1.0.3 py_0 conda-forge
sphinxcontrib-jsmath 1.0.1 py_0 conda-forge
sphinxcontrib-qthelp 1.0.2 py_0 conda-forge
sphinxcontrib-serializinghtml 1.1.3 py_0 conda-forge
sqlalchemy 1.3.11 py37h0b31af3_0 conda-forge
sqlite 3.30.1 h93121df_0 conda-forge
statsmodels 0.10.2 pypi_0 pypi
tbb 2018.0.5 h2d50403_0 conda-forge
tiledb 1.7.0 hd5e958f_2 conda-forge
tk 8.6.9 ha441bb4_1000 conda-forge
toml 0.10.0 py37h28b3542_0 
tornado 6.0.3 py37h0b31af3_0 conda-forge
traitlets 4.3.3 py37_0 conda-forge
typed-ast 1.4.1 py37h1de35cc_0 
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xerces-c 3.2.2 hbda6038_1004 conda-forge
xz 5.2.4 h1de35cc_1001 conda-forge
yaml 0.1.7 h1de35cc_1001 conda-forge
zlib 1.2.11 h0b31af3_1006 conda-forge
zstd 1.4.4 he7fca8b_1 conda-forge

[liamtoney]

However — the command

pygmt.config(MAP_FRAME_TYPE='fancy')

works as expected. Does FONT not have a default, usually?

[weiji14]

I'm not very familiar with GMT's settings, but looking at https://docs.generic-mapping-tools.org/latest/gmt.conf.html#font-parameters, it says:

FONT
Sets the default for all fonts, except FONT_LOGO. This setting is not included in the gmt.conf file.

so I guess that means there's no default? I think we'll need to wrap the below code around a try...except clause to handle these cases:

pygmt/pygmt/modules.py

Lines 166 to 168 in 5a5091e

	with Session() as lib:
	for key in kwargs:
	self.old_defaults[key] = lib.get_default(key)

[weiji14]

Ok, so there seems to be 7 settings without default settings. Besides FONT which influences all FONT_ related settings (except FONT_LOGO), the other 6 seems to only control both the resulting _PRIMARY and _SECONDARY settings (e.g. FONT_ANNOT_PRIMARY and FONT_ANNOT_SECONDARY).

• FONT_ANNOT
• FORMAT_TIME_MAP*
• MAP_ANNOT_OFFSET
• MAP_GRID_CROSS_SIZE
• MAP_TICK_LENGTH
• MAP_TICK_PEN

* FORMAT_TIME_PRIMARY_MAP, FORMAT_TIME_SECONDARY_MAP

I could do an 'allowlist' to map the 6 types above to their corresponding _PRIMARY and _SECONDARY settings, so that their default settings are reverted outside of the with block, but FONT itself will still be a bit tricky to handle. Any ideas?

[liamtoney]

Hmm, that's actually a tricky problem since we can't access FONT programmatically (what even is the default?). I guess for now we could do a try/except or if key == 'FONT' workaround to just not perform the error-raising lookup for the time-being?

I'm not familiar with context managers, but is there a way to raise an error if someone tries to set FONT using the with block? E.g. Error: Setting parameter "FONT" within a with block is not supported. That would be better in my view since it wouldn't just silently not revert the FONT value...

[seisman]

I could do an 'allowlist' to map the 6 types above to their corresponding _PRIMARY and _SECONDARY settings, so that their default settings are reverted outside of the with block, but FONT itself will still be a bit tricky to handle. Any ideas?

It's a good solution for me. For FONT, we probably have to maintain a list of FONT_* parameters.