Added properly functioning case insensitive match without regex

pandas.core.strings.str_contains should now match case insensitivity properly if given regex=False and case=False.  Also added test cases for case insensitive pandas.core.strings.str_contains with and without regex.

Author: benjwadams

pandas/core/strings.py

@@ -189,7 +189,12 @@ def str_contains(arr, pat, case=True, flags=0, na=np.nan, regex=True):
 
         f = lambda x: bool(regex.search(x))
     else:
-        f = lambda x: pat in x
+        if case:
+            f = lambda x: pat in x
+        else:
+            upper_pat = pat.upper()
+            f = lambda x: upper_pat in x
+            return _na_map(f, str_upper(arr), na, dtype=bool)
     return _na_map(f, arr, na, dtype=bool)
 
 

pandas/tests/test_strings.py

@@ -189,6 +189,17 @@ def test_contains(self):
         self.assertEqual(result.dtype, np.bool_)
         tm.assert_almost_equal(result, expected)
 
+        # case insensitive using regex
+        values = ['Foo', 'xYz', 'fOOomMm__fOo', 'MMM_']
+        result = strings.str_contains(values, 'FOO|mmm', case=False)
+        expected = [True, False, True, True]
+        tm.assert_almost_equal(result, expected)
+
+        # case insensitive without regex
+        result = strings.str_contains(values, 'foo', regex=False, case=False)
+        expected = [True, False, True, False]
+        tm.assert_almost_equal(result, expected)
+
         # mixed
         mixed = ['a', NA, 'b', True, datetime.today(), 'foo', None, 1, 2.]
         rs = strings.str_contains(mixed, 'o')