BUG: DataFrame.from_records bug with index column and empty record list. close #2633

Author: wesm

RELEASE.rst

@@ -82,6 +82,8 @@ pandas 0.10.1
  results (GH2599_)
  - Fix groupby summing performance issue on boolean data (GH2692_)
  - Don't bork Series containing datetime64 values with to_datetime (GH2699_)
+ - Fix DataFrame.from_records corner case when passed columns, index column,
+ but empty record list (GH2633_)
 
 **API Changes**
 
@@ -101,6 +103,7 @@ pandas 0.10.1
 .. _GH2616: https://github.com/pydata/pandas/issues/2616
 .. _GH2625: https://github.com/pydata/pandas/issues/2625
 .. _GH2643: https://github.com/pydata/pandas/issues/2643
+.. _GH2633: https://github.com/pydata/pandas/issues/2633
 .. _GH2637: https://github.com/pydata/pandas/issues/2637
 .. _GH2690: https://github.com/pydata/pandas/issues/2690
 .. _GH2692: https://github.com/pydata/pandas/issues/2692

pandas/core/frame.py

@@ -1030,7 +1030,10 @@ def from_records(cls, data, index=None, exclude=None, columns=None,
  not hasattr(index, "__iter__")):
  i = columns.get_loc(index)
  exclude.add(index)
- result_index = Index(arrays[i], name=index)
+ if len(arrays) > 0:
+ result_index = Index(arrays[i], name=index)
+ else:
+ result_index = Index([], name=index)
  else:
  try:
  to_remove = [arr_columns.get_loc(field) for field in index]
@@ -1043,9 +1046,11 @@ def from_records(cls, data, index=None, exclude=None, columns=None,
  result_index = index
 
  if any(exclude):
- to_remove = [arr_columns.get_loc(col) for col in exclude]
+ arr_exclude = [x for x in exclude if x in arr_columns]
+ to_remove = [arr_columns.get_loc(col) for col in arr_exclude]
  arrays = [v for i, v in enumerate(arrays) if i not in to_remove]
- arr_columns = arr_columns.drop(exclude)
+
+ arr_columns = arr_columns.drop(arr_exclude)
  columns = columns.drop(exclude)
 
  mgr = _arrays_to_mgr(arrays, arr_columns, result_index,

pandas/tests/test_frame.py

@@ -2928,6 +2928,15 @@ def __iter__(self):
  expected = DataFrame.from_records(tups)
  assert_frame_equal(result, expected)
 
+ def test_from_records_len0_with_columns(self):
+ # #2633
+ result = DataFrame.from_records([], index='foo',
+ columns=['foo', 'bar'])
+
+ self.assertTrue(np.array_equal(result.columns, ['bar']))
+ self.assertEqual(len(result), 0)
+ self.assertEqual(result.index.name, 'foo')
+
  def test_get_agg_axis(self):
  cols = self.frame._get_agg_axis(0)
  self.assert_(cols is self.frame.columns)