Merge pull request #10302 from evanpw/empty_index_name

BUG: read_csv does not set index name on an empty DataFrame

Author: jreback

doc/source/whatsnew/v0.16.2.txt

@@ -150,6 +150,7 @@ Bug Fixes
 - Bug in `plot` not defaulting to matplotlib `axes.grid` setting (:issue:`9792`)
 
 - Bug in ``Series.align`` resets ``name`` when ``fill_value`` is specified (:issue:`10067`)
+- Bug in ``read_csv`` causing index name not to be set on an empty DataFrame (:issue:`10184`)
 - Bug in ``SparseSeries.abs`` resets ``name`` (:issue:`10241`)
 - Bug in ``TimedeltaIndex`` slicing may reset freq (:issue:`10292`)
 

pandas/io/parsers.py

@@ -1170,7 +1170,9 @@ def read(self, nrows=None):
             data = self._reader.read(nrows)
         except StopIteration:
             if nrows is None:
-                return None, self.names, {}
+                return _get_empty_meta(self.orig_names,
+                                       self.index_col,
+                                       self.index_names)
             else:
                 raise
 

pandas/io/tests/test_parsers.py

@@ -2294,6 +2294,13 @@ def test_chunk_begins_with_newline_whitespace(self):
         result = self.read_csv(StringIO(data), header=None)
         self.assertEqual(len(result), 2)
 
+    def test_empty_with_index(self):
+        # GH 10184
+        data = 'x,y'
+        result = self.read_csv(StringIO(data), index_col=0)
+        expected = DataFrame([], columns=['y'], index=Index([], name='x'))
+        tm.assert_frame_equal(result, expected)
+
 
 class TestPythonParser(ParserTests, tm.TestCase):
     def test_negative_skipfooter_raises(self):