Support array-like mask in heatmaps (#3803)

* Support array-like mask in heatmaps

* Nit

seaborn/matrix.py

@@ -69,7 +69,14 @@ def _matrix_mask(data, mask):
     if mask is None:
         mask = np.zeros(data.shape, bool)
 
-    if isinstance(mask, np.ndarray):
+    if isinstance(mask, pd.DataFrame):
+        # For DataFrame masks, ensure that semantic labels match data
+        if not mask.index.equals(data.index) \
+           and mask.columns.equals(data.columns):
+            err = "Mask must have the same index and columns as data."
+            raise ValueError(err)
+    elif hasattr(mask, "__array__"):
+        mask = np.asarray(mask)
         # For array masks, ensure that shape matches data then convert
         if mask.shape != data.shape:
             raise ValueError("Mask must have the same shape as data.")
@@ -79,13 +86,6 @@ def _matrix_mask(data, mask):
                             columns=data.columns,
                             dtype=bool)
 
-    elif isinstance(mask, pd.DataFrame):
-        # For DataFrame masks, ensure that semantic labels match data
-        if not mask.index.equals(data.index) \
-           and mask.columns.equals(data.columns):
-            err = "Mask must have the same index and columns as data."
-            raise ValueError(err)
-
     # Add any cells with missing data to the mask
     # This works around an issue where `plt.pcolormesh` doesn't represent
     # missing data properly

tests/test_matrix.py

@@ -56,6 +56,24 @@ def test_ndarray_input(self):
         assert p.xlabel == ""
         assert p.ylabel == ""
 
+    def test_array_like_input(self):
+        class ArrayLike:
+            def __init__(self, data):
+                self.data = data
+
+            def __array__(self, dtype=None, copy=None):
+                return np.asarray(self.data, dtype=dtype, copy=copy)
+
+        p = mat._HeatMapper(ArrayLike(self.x_norm), **self.default_kws)
+        npt.assert_array_equal(p.plot_data, self.x_norm)
+        pdt.assert_frame_equal(p.data, pd.DataFrame(self.x_norm))
+
+        npt.assert_array_equal(p.xticklabels, np.arange(8))
+        npt.assert_array_equal(p.yticklabels, np.arange(4))
+
+        assert p.xlabel == ""
+        assert p.ylabel == ""
+
     def test_df_input(self):
 
         p = mat._HeatMapper(self.df_norm, **self.default_kws)