Transform not working with xlim / ylim and col_wrap

[sarahclaude]

What happened?

I get back the wrong projections when passing transform with col_wrap = 2 while plotting a facetgrid (first picture).
I also get empty subplots when using transform = ccrs.PlateCarrree with a defined xlim and ylim (second picture).

What did you expect to happen?

Minimal Complete Verifiable Example

import xarray as xr

url = 'https://pavics.ouranos.ca//twitcher/ows/proxy/thredds/dodsC/birdhouse/disk2/cccs_portal/indices/Final/BCCAQv2_CMIP6/tx_max/YS/ssp585/ensemble_percentiles/tx_max_ann_BCCAQ2v2+ANUSPLIN300_historical+ssp585_1950-2100_30ymean_percentiles.nc'

opened = xr.open_dataset(url, decode_timedelta=False)
ds_space = opened[['tx_max_p50']].isel(time=[0, 1, 2]).sel(lat=slice(40,65), lon=slice(-90,-55))

#transform with col_wrap
ds_space['tx_max_p50'].plot(**{"x": "lon", "y": "lat", "col": "time", 'col_wrap':2},
                            subplot_kws={"projection": ccrs.LambertConformal()},
                            transform = ccrs.PlateCarree()
                           )

#transform and xlim/ylim
ds_space['tx_max_p50'].plot(**{"x": "lon", "y": "lat", "col": "time", 
"xlim": [-70, -75], "ylim": [45, 50]},
                            subplot_kws={"projection": ccrs.LambertConformal()},
                            transform = ccrs.PlateCarree()
                           )

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.
• Recent environment — the issue occurs with the latest version of xarray and its dependencies.

Relevant log output

No response

Anything else we need to know?

No response

Environment

commit: None python: 3.11.0 | packaged by conda-forge | (main, Jan 14 2023, 12:27:40) [GCC 11.3.0] python-bits: 64 OS: Linux OS-release: 6.2.0-39-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: fr_CA.UTF-8 LOCALE: ('fr_CA', 'UTF-8') libhdf5: 1.14.0 libnetcdf: 4.9.2

xarray: 2023.10.1
pandas: 2.0.2
numpy: 1.24.3
scipy: 1.10.1
netCDF4: 1.6.4
pydap: None
h5netcdf: None
h5py: 3.8.0
Nio: None
zarr: 2.15.0
cftime: 1.6.2
nc_time_axis: None
PseudoNetCDF: None
iris: None
bottleneck: 1.3.7
dask: 2023.6.0
distributed: 2023.6.0
matplotlib: 3.7.1
cartopy: 0.21.1
seaborn: 0.12.2
numbagg: None
fsspec: 2023.6.0
cupy: None
pint: 0.22
sparse: None
flox: None
numpy_groupies: None
setuptools: 67.7.2
pip: 23.1.2
conda: None
pytest: 7.3.2
mypy: None
IPython: 8.14.0
sphinx: 7.0.1

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[kmuehlbauer]

@sarahclaude Thanks for providing the MCVE. I've converted this to a discussion under Q&A as this is technically not a bug.

Your source data is in longitude/latitude but your rendered images are as requested in lambert conformal projection. Setting xlim and ylim would technically need the limits provided in lambert conformal coordinates.

It might make more sense to slice the source data to the wanted ranges before plotting. At least I do not know another solution immediately.

[kmuehlbauer]

I was probably too fast converting this to Q&A. Sorry @sarahclaude. The col_wrap=2 thing is an issue, I get working plots with either col_wrap=1 or col_wrap=3. Wrong numbers are returned in FacetGrid._get_largest_lims() probably due to the one empty axes.

Update:

It looks like FacetGrid does have some problems with sharex/sharey in connection with empty axes in the facet grid. We would get along by setting the extent for all axes like this:

g = ds_space['tx_max_p50'].plot(**{"x": "lon", "y": "lat", "col": "time", "col_wrap": 2,},
                            subplot_kws={"projection": ccrs.LambertConformal()},
                            transform = ccrs.PlateCarree()
                           )
for ax in g.axs.flat:
    ax.set_extent((-75, -70, 45, 50))