Use parent collections norm for constant arrays

andrewdnolan · andrewdnolan · commit 3998a28ab153 · 2025-11-05T21:04:42.000-07:00
When mirroring constant array the norm somehow end up being
different for constant arrays. It's strange and seems to be
something fairly low level in matplotlib. So as a fix, if plotting
constant arrays use the parents norm for the mirrored collection.
diff --git a/mosaic/polypcolor.py b/mosaic/polypcolor.py
@@ -64,6 +64,9 @@ def _mirror_polycollection(ax, collection, descriptor, array, **kwargs):
         mirrored_verts, array=array[mirrored_idxs], zorder=zorder, **kwargs
     )
 
+    if np.allclose(array, array[0], rtol=1e-8, atol=1e-10):
+        norm = collection.norm
+
     mirrored_collection.set_cmap(cmap)
     mirrored_collection.set_norm(norm)
     mirrored_collection.set_clim(vmin, vmax)

Original file line number	Diff line number	Diff line change
`@@ -64,6 +64,9 @@ def _mirror_polycollection(ax, collection, descriptor, array, **kwargs):`
`64`	`64`	`mirrored_verts, array=array[mirrored_idxs], zorder=zorder, **kwargs`
`65`	`65`	`)`
`66`	`66`
	`67`	`+ if np.allclose(array, array[0], rtol=1e-8, atol=1e-10):`
	`68`	`+ norm = collection.norm`
	`69`	`+`
`67`	`70`	`mirrored_collection.set_cmap(cmap)`
`68`	`71`	`mirrored_collection.set_norm(norm)`
`69`	`72`	`mirrored_collection.set_clim(vmin, vmax)`