DOC: add note about axes order to docstring

Author: tacaswell

lib/matplotlib/figure.py

@@ -1738,7 +1738,9 @@ def subplot_mosaic(self, layout, *, subplot_kw=None, gridspec_kw=None,
         Returns
         -------
         dict[label, Axes]
-           A dictionary mapping the labels to the Axes objects.
+           A dictionary mapping the labels to the Axes objects.  The order of
+           the axes is left-to-right and top-to-bottom of their position in the
+           total layout.
 
         """
         subplot_kw = subplot_kw or {}

lib/matplotlib/pyplot.py

@@ -1500,7 +1500,9 @@ def subplot_mosaic(layout, *, subplot_kw=None, gridspec_kw=None,
        The new figure
 
     dict[label, Axes]
-       A dictionary mapping the labels to the Axes objects.
+       A dictionary mapping the labels to the Axes objects.  The order of
+       the axes is left-to-right and top-to-bottom of their position in the
+       total layout.
 
     """
     fig = figure(**fig_kw)