FIX

jklymak · jklymak · commit 3a43af7b8ed6 · 2021-11-19T15:20:58.000+01:00
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
@@ -1150,15 +1150,17 @@ def _mesh(self):
 
     def _forward_boundaries(self, x):
         b = self._boundaries
-        y = np.interp(x, b, np.linspace(0, b[-1]-b[0], len(b)))
-        eps = (b[-1] - b[0]) * 1e-6
-        y[x < b[0]-eps] = -1
-        y[x > b[-1]+eps] = 2
+        db = b[-1] - b[0]
+        y = np.interp(x, b, np.linspace(0, db, len(b)))
+        # the following avoids ticks in the extends:
+        eps = db * 1e-6
+        y[x < b[0]-eps] = -1 * db
+        y[x > b[-1]+eps] = b[-1] + db
         return y
 
     def _inverse_boundaries(self, x):
         b = self._boundaries
-        return np.interp(x, np.linspace(0, b[-1], len(b)), b)
+        return np.interp(x, np.linspace(0, b[-1]-b[0], len(b)), b)
 
     def _reset_locator_formatter_scale(self):
         """
