BUG: Use context manager; add test from pandas-dev#17776

yeemey · Oct 13, 2017 · 039315a · 039315a
1 parent 5c5acd1
commit 039315a
Show file tree

Hide file tree

Showing 2 changed files with 10 additions and 4 deletions.
diff --git a/pandas/core/reshape/merge.py b/pandas/core/reshape/merge.py
@@ -1514,7 +1514,6 @@ def _sort_labels(uniques, left, right):
 
 
 def _get_join_keys(llab, rlab, shape, sort):
-    np.seterr(divide='ignore')
 
     # how many levels can be done without overflow
     pred = lambda i: not is_int64_overflow_possible(shape[:i])
@@ -1526,10 +1525,10 @@ 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
-    np.seterr(divide='warn')
 
     if nlev == len(shape):  # all done!
         return lkey, rkey

diff --git a/pandas/tests/reshape/test_merge.py b/pandas/tests/reshape/test_merge.py
@@ -860,7 +860,14 @@ 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
+        import warnings
+        a = pd.DataFrame({'a':[], 'b':[], 'c':[]})
+        with warnings.catch_warnings(record=True) as record:
+            merge(a, a, on=('a', 'b'))
+            assert len(record) == 0        
 
 def _check_merge(x, y):
     for how in ['inner', 'left', 'outer']: