Merge pull request #7328 from jreback/div_error

BUG: Bug in broadcasting with .div, integer dtypes and divide-by-zero (GH7325)

Author: jreback

doc/source/v0.14.1.txt

@@ -87,3 +87,4 @@ Bug Fixes
   (:issue:`7315`).
 - Bug in inferred_freq results in None for eastern hemisphere timezones (:issue:`7310`)
 - Bug in ``Easter`` returns incorrect date when offset is negative (:issue:`7195`)
+- Bug in broadcasting with ``.div``, integer dtypes and divide-by-zero (:issue:`7325`)

pandas/core/common.py

@@ -1244,20 +1244,21 @@ def _fill_zeros(result, x, y, name, fill):
 
         if is_integer_dtype(y):
 
-            mask = y.ravel() == 0
-            if mask.any():
+            if (y.ravel() == 0).any():
                 shape = result.shape
                 result = result.ravel().astype('float64')
 
+                # GH 7325, mask and nans must be broadcastable
                 signs = np.sign(result)
-                nans = np.isnan(x.ravel())
-                np.putmask(result, mask & ~nans, fill)
+                mask = ((y == 0) & ~np.isnan(x)).ravel()
+
+                np.putmask(result, mask, fill)
 
                 # if we have a fill of inf, then sign it
                 # correctly
                 # GH 6178
                 if np.isinf(fill):
-                    np.putmask(result,signs<0 & mask & ~nans,-fill)
+                    np.putmask(result,signs<0 & mask, -fill)
 
                 result = result.reshape(shape)
 

pandas/tests/test_frame.py

@@ -5240,6 +5240,17 @@ def test_arith_flex_series(self):
         assert_frame_equal(df.div(row), df / row)
         assert_frame_equal(df.div(col, axis=0), (df.T / col).T)
 
+        # broadcasting issue in GH7325
+        df = DataFrame(np.arange(3*2).reshape((3,2)),dtype='int64')
+        expected = DataFrame([[np.inf,np.inf],[1.0,1.5],[1.0,1.25]])
+        result = df.div(df[0],axis='index')
+        assert_frame_equal(result,expected)
+
+        df = DataFrame(np.arange(3*2).reshape((3,2)),dtype='float64')
+        expected = DataFrame([[np.nan,np.inf],[1.0,1.5],[1.0,1.25]])
+        result = df.div(df[0],axis='index')
+        assert_frame_equal(result,expected)
+
     def test_arith_non_pandas_object(self):
         df = self.simple