Display coords' units for slice plots

doc/whats-new.rst

@@ -36,6 +36,8 @@ New Features
   `Nathan Lis <https://github.com/wxman22>`_.
 - Histogram plots are set with a title displaying the scalar coords if any, similarly to the other plots (:issue:`5791`, :pull:`5792`).
   By `Maxime Liquet <https://github.com/maximlt>`_.
+- Slice plots display the coords units in the same way as x/y/colorbar labels (:pull:`5847`).
+  By `Victor Negîrneac <https://github.com/caenrigen>`_.
 
 Breaking changes
 ~~~~~~~~~~~~~~~~

xarray/core/dataarray.py

@@ -22,6 +22,7 @@
 import pandas as pd
 
 from ..plot.plot import _PlotMethods
+from ..plot.utils import _get_units_from_attrs
 from . import (
     computation,
     dtypes,
@@ -3108,7 +3109,11 @@ def _title_for_slice(self, truncate: int = 50) -> str:
         for dim, coord in self.coords.items():
             if coord.size == 1:
                 one_dims.append(
-                    "{dim} = {v}".format(dim=dim, v=format_item(coord.values))
+                    "{dim} = {v}{unit}".format(
+                        dim=dim,
+                        v=format_item(coord.values),
+                        unit=_get_units_from_attrs(coord),
+                    )
                 )
 
         title = ", ".join(one_dims)

xarray/plot/utils.py

@@ -468,6 +468,21 @@ def _maybe_gca(**kwargs):
     return plt.axes(**kwargs)
 
 
+def _get_units_from_attrs(da):
+    """Extracts and formats the unit/units from a attributes."""
+    pint_array_type = DuckArrayModule("pint").type
+    units = " [{}]"
+    if isinstance(da.data, pint_array_type):
+        units = units.format(str(da.data.units))
+    elif da.attrs.get("units"):
+        units = units.format(da.attrs["units"])
+    elif da.attrs.get("unit"):
+        units = units.format(da.attrs["unit"])
+    else:
+        units = ""
+    return units
+
+
 def label_from_attrs(da, extra=""):
     """Makes informative labels if variable metadata (attrs) follows
     CF conventions."""
@@ -481,20 +496,7 @@ def label_from_attrs(da, extra=""):
     else:
         name = ""
 
-    def _get_units_from_attrs(da):
-        if da.attrs.get("units"):
-            units = " [{}]".format(da.attrs["units"])
-        elif da.attrs.get("unit"):
-            units = " [{}]".format(da.attrs["unit"])
-        else:
-            units = ""
-        return units
-
-    pint_array_type = DuckArrayModule("pint").type
-    if isinstance(da.data, pint_array_type):
-        units = " [{}]".format(str(da.data.units))
-    else:
-        units = _get_units_from_attrs(da)
+    units = _get_units_from_attrs(da)
 
     # Treat `name` differently if it's a latex sequence
     if name.startswith("$") and (name.count("$") % 2 == 0):