ENH: indexing and __getitem__ of dataframe and series accept zerodim integer np.array as int

doc/source/whatsnew/v0.25.0.rst

@@ -28,6 +28,25 @@ Backwards incompatible API changes
 
 .. _whatsnew_0250.api.other:
 
+Indexing and getitem
+^^^^^^^^^^^^^^^^^^^^
+
+Indexing and getitem of pd.DataFrame now accept zerodim np.array.
+
+.. ipython:: python
+    df = pd.DataFrame([[1, 2], [3, 4]])[np.array(0)]
+    df.iloc[np.array(0)]
+    df.loc[np.array(0)]
+    df[np.array(0)]
+
+Indexing and getitem of pd.Series now accept zerodim np.array.
+
+.. ipython:: python
+    sr = pd.Series([1, 2])
+    sr.iloc[np.array(0)]
+    sr.loc[np.array(0)]
+    sr[np.array(0)]
+
 Other API Changes
 ^^^^^^^^^^^^^^^^^
 

pandas/core/frame.py

@@ -2881,6 +2881,7 @@ def _ixs(self, i, axis=0):
                 return result
 
     def __getitem__(self, key):
+        key = lib.item_from_zerodim(key)
         key = com.apply_if_callable(key, self)
 
         # shortcut if the key is in columns

pandas/core/indexing.py

@@ -5,6 +5,7 @@
 import numpy as np
 
 from pandas._libs.indexing import _NDFrameIndexerBase
+from pandas._libs.lib import item_from_zerodim
 import pandas.compat as compat
 from pandas.compat import range, zip
 from pandas.errors import AbstractMethodError
@@ -1856,6 +1857,7 @@ def _getitem_axis(self, key, axis=None):
         if axis is None:
             axis = self.axis or 0
 
+        key = item_from_zerodim(key)
         if is_iterator(key):
             key = list(key)
 
@@ -2222,6 +2224,7 @@ def _getitem_axis(self, key, axis=None):
 
         # a single integer
         else:
+            key = item_from_zerodim(key)
             if not is_integer(key):
                 raise TypeError("Cannot index by location index with a "
                                 "non-integer key")

pandas/tests/frame/test_indexing.py

@@ -3682,3 +3682,14 @@ def test_functions_no_warnings(self):
         with tm.assert_produces_warning(False):
             df['group'] = pd.cut(df.value, range(0, 105, 10), right=False,
                                  labels=labels)
+
+    def test_getitem_zerodim_np_array(self):
+        # GH24924
+        df = DataFrame([[1, 2], [3, 4]])
+
+        # should not raise an error
+        result = df[np.array(0)]
+
+        # expected series
+        sr = pd.Series([1, 3], name=0)
+        tm.assert_series_equal(result, sr)

pandas/tests/indexing/test_iloc.py

@@ -675,3 +675,23 @@ def test_identity_slice_returns_new_object(self):
         # should also be a shallow copy
         original_series[:3] = [7, 8, 9]
         assert all(sliced_series[:3] == [7, 8, 9])
+
+    def test_indexing_zero_dim_np_array(self):
+        # GH24919
+        df = DataFrame([[1, 2], [3, 4]])
+
+        # should not raise an error
+        result = df.iloc[np.array(0)]
+
+        # expected series
+        sr = pd.Series([1, 2], name=0)
+        tm.assert_series_equal(result, sr)
+
+    def test_series_indexing_zero_dim_np_array(self):
+        # GH24919
+        sr = Series([1, 2])
+
+        # should not raise an error
+        result = sr.iloc[np.array(0)]
+
+        assert result == 1

pandas/tests/indexing/test_loc.py

@@ -765,3 +765,23 @@ def test_loc_setitem_empty_append_raises(self):
         msg = "cannot copy sequence with size 2 to array axis with dimension 0"
         with pytest.raises(ValueError, match=msg):
             df.loc[0:2, 'x'] = data
+
+    def test_indexing_zero_dim_np_array(self):
+        # GH24924
+        df = DataFrame([[1, 2], [3, 4]])
+
+        # should not raise an error
+        result = df.loc[np.array(0)]
+
+        # expected series
+        sr = pd.Series([1, 2], name=0)
+        tm.assert_series_equal(result, sr)
+
+    def test_series_indexing_zero_dim_np_array(self):
+        # GH24924
+        sr = Series([1, 2])
+
+        # should not raise an error
+        result = sr.loc[np.array(0)]
+
+        assert result == 1

pandas/tests/series/indexing/test_indexing.py

@@ -838,3 +838,13 @@ def test_head_tail(test_data):
     assert_series_equal(test_data.series.head(0), test_data.series[0:0])
     assert_series_equal(test_data.series.tail(), test_data.series[-5:])
     assert_series_equal(test_data.series.tail(0), test_data.series[0:0])
+
+
+def test_getitem_with_zerodim_np_array():
+    # GH24924
+    sr = Series([1, 2])
+
+    # should not raise an error
+    result = sr[np.array(0)]
+
+    assert result == 1