BUG: Ignore division by 0 when merging empty dataframes (pandas-dev#1…

…7776)
yeemey · Oct 16, 2017 · bbf1849 · bbf1849
1 parent 5c0b20a
commit bbf1849
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Showing 2 changed files with 8 additions and 1 deletion.
diff --git a/pandas/core/reshape/merge.py b/pandas/core/reshape/merge.py
@@ -1525,7 +1525,8 @@ def _get_join_keys(llab, rlab, shape, sort):
     rkey = stride * rlab[0].astype('i8', subok=False, copy=False)
 
     for i in range(1, nlev):
-        stride //= shape[i]
+        with np.errstate(divide='ignore'):
+            stride //= shape[i]
         lkey += llab[i] * stride
         rkey += rlab[i] * stride
 

diff --git a/pandas/tests/reshape/test_merge.py b/pandas/tests/reshape/test_merge.py
@@ -861,6 +861,12 @@ def test_validation(self):
         result = merge(left, right, on=['a', 'b'], validate='1:1')
         assert_frame_equal(result, expected_multi)
 
+    def test_merge_two_empty_df_no_division_error(self):
+        # GH17776, PR #17846
+        a = pd.DataFrame({'a': [], 'b': [], 'c': []})
+        with np.errstate(divide='raise'):
+            merge(a, a, on=('a', 'b'))
+
 
 def _check_merge(x, y):
     for how in ['inner', 'left', 'outer']: