ENH: Allow literal (non-regex) replacement using .str.replace pandas-…

…dev#16808

pandas/tests/test_strings.py

@@ -431,6 +431,16 @@ def test_replace(self):
                     values = klass(data)
                     pytest.raises(TypeError, values.str.replace, 'a', repl)
 
+        # GH16808 literal replace (regex=False vs regex=True)
+        values = Series(['f.o', 'foo', NA])
+        exp = Series(['bao', 'bao', NA])
+        result = values.str.replace('f.', 'ba')
+        tm.assert_series_equal(result, exp)
+
+        exp = Series(['bao', 'foo', NA])
+        result = values.str.replace('f.', 'ba', regex=False)
+        tm.assert_series_equal(result, exp)
+
     def test_replace_callable(self):
         # GH 15055
         values = Series(['fooBAD__barBAD', NA])
@@ -441,6 +451,8 @@ def test_replace_callable(self):
         exp = Series(['foObaD__baRbaD', NA])
         tm.assert_series_equal(result, exp)
 
+        pytest.raises(ValueError, values.str.replace, 'abc', repl, regex=False)
+
         # test with wrong number of arguments, raising an error
         if compat.PY2:
             p_err = r'takes (no|(exactly|at (least|most)) ?\d+) arguments?'
@@ -522,6 +534,8 @@ def test_replace_compiled_regex(self):
                                     "case and flags cannot be"):
             result = values.str.replace(pat, '', case=True)
 
+        pytest.raises(ValueError, values.str.replace, pat, '', regex=False)
+
         # test with callable
         values = Series(['fooBAD__barBAD', NA])
         repl = lambda m: m.group(0).swapcase()