Prefer tr1-tr2 to tr1+tr2.inverted().

anntzer · anntzer · commit 9ae6f0e62e37 · 2021-02-10T10:24:27.000+01:00
As discussed elsewhere, the first form is both faster and more accurate
as it can handle exact cancellations.
diff --git a/lib/matplotlib/lines.py b/lib/matplotlib/lines.py
@@ -1432,8 +1432,7 @@ def __init__(self, xy1, xy2, slope, **kwargs):
 
     def get_transform(self):
         ax = self.axes
-        points_transform = (self._transform + ax.transData.inverted() +
-                            ax.transScale)
+        points_transform = self._transform - ax.transData + ax.transScale
 
         if self._xy2 is not None:
             # two points were given
