Merge pull request #15187 from dstansby/15140-backport

tacaswell · web-flow · commit c615fd499619 · 2019-09-04T15:46:01.000-04:00
Backport PR #15140 on branch v3.1.x
diff --git a/lib/matplotlib/tests/test_image.py b/lib/matplotlib/tests/test_image.py
@@ -989,3 +989,18 @@ def test_deprecation():
         with pytest.warns(MatplotlibDeprecationWarning):
             # Enough arguments to pass "shape" positionally.
             obj.imshow(data, *[None] * 10)
+
+
+def test_image_cursor_formatting():
+    fig, ax = plt.subplots()
+    # Create a dummy image to be able to call format_cursor_data
+    im = ax.imshow(np.zeros((4, 4)))
+
+    data = np.ma.masked_array([0], mask=[True])
+    assert im.format_cursor_data(data) == '[]'
+
+    data = np.ma.masked_array([0], mask=[False])
+    assert im.format_cursor_data(data) == '[0]'
+
+    data = np.nan
+    assert im.format_cursor_data(data) == '[nan]'
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -629,6 +629,8 @@ def format_data_short(self, value):
         """
         if self._useLocale:
             return locale.format_string('%-12g', (value,))
+        elif isinstance(value, np.ma.MaskedArray) and value.mask:
+            return ''
         else:
             return '%-12g' % value
 
