FIX: fix equal spaced

jklymak · jklymak · commit 6423cc5686cd · 2021-11-19T12:51:31.000+01:00
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
@@ -1150,7 +1150,7 @@ def _mesh(self):
 
     def _forward_boundaries(self, x):
         b = self._boundaries
-        y = np.interp(x, b, np.linspace(0, np.abs(b[-1]), len(b)))
+        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
diff --git a/lib/matplotlib/tests/test_colorbar.py b/lib/matplotlib/tests/test_colorbar.py
@@ -894,3 +894,10 @@ def test_negative_boundarynorm():
     cb = fig.colorbar(cm.ScalarMappable(cmap=cmap, norm=norm), cax=ax)
     np.testing.assert_allclose(cb.ax.get_ylim(), [clevs[0], clevs[-1]])
     np.testing.assert_allclose(cb.ax.get_yticks(), clevs)
+
+    clevs = np.arange(-8, 1)
+    norm = BoundaryNorm(clevs, cmap.N)
+    cb = fig.colorbar(cm.ScalarMappable(cmap=cmap, norm=norm), cax=ax)
+    np.testing.assert_allclose(cb.ax.get_ylim(), [clevs[0], clevs[-1]])
+    np.testing.assert_allclose(cb.ax.get_yticks(), clevs)
+
