BUG: Concat with axis rows

closes #14369 Author: Brandon M. Burroughs <brandonmburroughs@gmail.com> Closes #14416 from brandonmburroughs/concat_with_axis_rows and squashes the following commits: 9aa260d [Brandon M. Burroughs] Changing axis handling to depend on object passed 49442be [Brandon M. Burroughs] Using dataframe _get_axis_number instance method 64702fb [Brandon M. Burroughs] Updating documentation for concat fdd5260 [Brandon M. Burroughs] Removing duplicate expected dfs 3f08b07 [Brandon M. Burroughs] Adding concat tests for axis 0, 1, and 'index' cf3f998 [Brandon M. Burroughs] Adding ValueError test for concat Series axis 'columns' a6694b9 [Brandon M. Burroughs] Updating documentation 584ebd2 [Brandon M. Burroughs] BUG: Allow concat to take string axis names

Author: brandonmburroughs

doc/source/whatsnew/v0.19.1.txt

@@ -44,6 +44,7 @@ Bug Fixes
 
 
 - Bug in ``pd.concat`` where names of the ``keys`` were not propagated to the resulting ``MultiIndex`` (:issue:`14252`)
+- Bug in ``pd.concat`` where ``axis`` cannot take string parameters ``'rows'`` or ``'columns'`` (:issue:`14369`)
 - Bug in ``MultiIndex.set_levels`` where illegal level values were still set after raising an error (:issue:`13754`)
 - Bug in ``DataFrame.to_json`` where ``lines=True`` and a value contained a ``}`` character (:issue:`14391`)
 - Bug in ``df.groupby`` causing an ``AttributeError`` when grouping a single index frame by a column and the index level (:issue`14327`)

pandas/tests/frame/test_combine_concat.py

@@ -347,6 +347,65 @@ def test_concat_named_keys(self):
  names=[None, None]))
  assert_frame_equal(concatted_unnamed, expected_unnamed)
 
+ def test_concat_axis_parameter(self):
+ # GH 14369
+ df1 = pd.DataFrame({'A': [0.1, 0.2]}, index=range(2))
+ df2 = pd.DataFrame({'A': [0.3, 0.4]}, index=range(2))
+
+ # Index/row/0 DataFrame
+ expected_index = pd.DataFrame(
+ {'A': [0.1, 0.2, 0.3, 0.4]}, index=[0, 1, 0, 1])
+
+ concatted_index = pd.concat([df1, df2], axis='index')
+ assert_frame_equal(concatted_index, expected_index)
+
+ concatted_row = pd.concat([df1, df2], axis='rows')
+ assert_frame_equal(concatted_row, expected_index)
+
+ concatted_0 = pd.concat([df1, df2], axis=0)
+ assert_frame_equal(concatted_0, expected_index)
+
+ # Columns/1 DataFrame
+ expected_columns = pd.DataFrame(
+ [[0.1, 0.3], [0.2, 0.4]], index=[0, 1], columns=['A', 'A'])
+
+ concatted_columns = pd.concat([df1, df2], axis='columns')
+ assert_frame_equal(concatted_columns, expected_columns)
+
+ concatted_1 = pd.concat([df1, df2], axis=1)
+ assert_frame_equal(concatted_1, expected_columns)
+
+ series1 = pd.Series([0.1, 0.2])
+ series2 = pd.Series([0.3, 0.4])
+
+ # Index/row/0 Series
+ expected_index_series = pd.Series(
+ [0.1, 0.2, 0.3, 0.4], index=[0, 1, 0, 1])
+
+ concatted_index_series = pd.concat([series1, series2], axis='index')
+ assert_series_equal(concatted_index_series, expected_index_series)
+
+ concatted_row_series = pd.concat([series1, series2], axis='rows')
+ assert_series_equal(concatted_row_series, expected_index_series)
+
+ concatted_0_series = pd.concat([series1, series2], axis=0)
+ assert_series_equal(concatted_0_series, expected_index_series)
+
+ # Columns/1 Series
+ expected_columns_series = pd.DataFrame(
+ [[0.1, 0.3], [0.2, 0.4]], index=[0, 1], columns=[0, 1])
+
+ concatted_columns_series = pd.concat(
+ [series1, series2], axis='columns')
+ assert_frame_equal(concatted_columns_series, expected_columns_series)
+
+ concatted_1_series = pd.concat([series1, series2], axis=1)
+ assert_frame_equal(concatted_1_series, expected_columns_series)
+
+ # Testing ValueError
+ with assertRaisesRegexp(ValueError, 'No axis named'):
+ pd.concat([series1, series2], axis='something')
+
 
 class TestDataFrameCombineFirst(tm.TestCase, TestData):
 

pandas/tools/merge.py

@@ -1283,7 +1283,7 @@ def concat(objs, axis=0, join='outer', join_axes=None, ignore_index=False,
  argument, unless it is passed, in which case the values will be
  selected (see below). Any None objects will be dropped silently unless
  they are all None in which case a ValueError will be raised
- axis : {0, 1, ...}, default 0
+ axis : {0/'index', 1/'columns'}, default 0
  The axis to concatenate along
  join : {'inner', 'outer'}, default 'outer'
  How to handle indexes on other axis(es)
@@ -1411,6 +1411,12 @@ def __init__(self, objs, axis=0, join='outer', join_axes=None,
  sample = objs[0]
  self.objs = objs
 
+ # Standardize axis parameter to int
+ if isinstance(sample, Series):
+ axis = DataFrame()._get_axis_number(axis)
+ else:
+ axis = sample._get_axis_number(axis)
+
  # Need to flip BlockManager axis in the DataFrame special case
  self._is_frame = isinstance(sample, DataFrame)
  if self._is_frame: