Improves rendering of complex LaTeX expressions as long_names when …

…plotting (#5682)

* try to wrap texts differently if they're latex code

* added space around modulo operator

* prevents breaking up of long words

* added test for label_from_attrs() function with a long latex string

* Update xarray/plot/utils.py

Co-authored-by: Illviljan <14371165+Illviljan@users.noreply.github.com>

* Update xarray/tests/test_utils.py

Co-authored-by: Illviljan <14371165+Illviljan@users.noreply.github.com>

* moved test_latex_name_isnt_split() to test_plots

* Apply suggestions from code review

* fixed test_latex_name_isnt_split()

* ran code through pre-commit

* updated whats-new.rst

Co-authored-by: Illviljan <14371165+Illviljan@users.noreply.github.com>
Co-authored-by: Deepak Cherian <dcherian@users.noreply.github.com>

doc/whats-new.rst

@@ -22,6 +22,8 @@ v0.19.1 (unreleased)
 
 New Features
 ~~~~~~~~~~~~
+- Xarray now does a better job rendering variable names that are long LaTeX sequences when plotting (:issue:`5681`, :pull:`5682`).
+  By `Tomas Chor <https://github.com/tomchor>`_.
 - Add a option to disable the use of ``bottleneck`` (:pull:`5560`)
   By `Justus Magin <https://github.com/keewis>`_.
 - Added ``**kwargs`` argument to :py:meth:`open_rasterio` to access overviews (:issue:`3269`).

xarray/plot/utils.py

@@ -490,7 +490,13 @@ def _get_units_from_attrs(da):
     else:
         units = _get_units_from_attrs(da)
 
-    return "\n".join(textwrap.wrap(name + extra + units, 30))
+    # Treat `name` differently if it's a latex sequence
+    if name.startswith("$") and (name.count("$") % 2 == 0):
+        return "$\n$".join(
+            textwrap.wrap(name + extra + units, 60, break_long_words=False)
+        )
+    else:
+        return "\n".join(textwrap.wrap(name + extra + units, 30))
 
 
 def _interval_to_mid_points(array):

xarray/tests/test_plot.py

@@ -2950,3 +2950,10 @@ def test_datarray_scatter(x, y, z, hue, markersize, row, col, add_legend, add_co
             add_legend=add_legend,
             add_colorbar=add_colorbar,
         )
+
+
+def test_latex_name_isnt_split():
+    da = xr.DataArray()
+    long_latex_name = r"$Ra_s = \mathrm{mean}(\epsilon_k) / \mu M^2_\infty$"
+    da.attrs = dict(long_name=long_latex_name)
+    assert label_from_attrs(da) == long_latex_name