BUG: don't need to convert numeric types already handled by converters, GH #546

Author: wesm

pandas/io/parsers.py

@@ -475,6 +475,9 @@ def _convert_to_ndarrays(dct, na_values):
     return result
 
 def _convert_types(values, na_values):
+    if issubclass(values.dtype.type, (np.number, np.bool_)):
+        return values
+
     try:
         values = lib.maybe_convert_numeric(values, na_values)
     except Exception:

pandas/io/tests/test_parsers.py

@@ -451,6 +451,13 @@ def test_converters(self):
         assert_frame_equal(result, expected)
         assert_frame_equal(result2, expected)
 
+        # produce integer
+        converter = lambda x: int(x.split('/')[2])
+        result = read_csv(StringIO(data), converters={'D' : converter})
+        expected = read_csv(StringIO(data))
+        expected['D'] = expected['D'].map(converter)
+        assert_frame_equal(result, expected)
+
     def test_regex_separator(self):
         data = """   A   B   C   D
 a   1   2   3   4

vb_suite/groupby.py

@@ -38,7 +38,7 @@ def f():
                                  name="groupby_multi_cython",
                                  start_date=datetime(2011, 7, 1))
 
-stmt = "df.groupby(['key1', 'key2'])['data1'].agg(Series.skew)"
+stmt = "df.groupby(['key1', 'key2'])['data1'].agg(np.std)"
 groupby_multi_series_op = Benchmark(stmt, setup,
                                     name="groupby_multi_series_op",
                                     start_date=datetime(2011, 8, 1))