Use a dedicated indexing.pyx module in pandas._libs

Author: Antoine Pitrou

pandas/_libs/indexing.pyx

@@ -0,0 +1,22 @@
+# cython: profile=False
+
+cdef class _NDFrameIndexerBase:
+    '''
+    A base class for _NDFrameIndexer for fast instantiation and attribute
+    access.
+    '''
+    cdef public object obj, name, _ndim
+
+    def __init__(self, name, obj):
+        self.obj = obj
+        self.name = name
+        self._ndim = None
+
+    @property
+    def ndim(self):
+        # Delay `ndim` instantiation until required as reading it
+        # from `obj` isn't entirely cheap.
+        ndim = self._ndim
+        if ndim is None:
+            ndim = self._ndim = self.obj.ndim
+        return ndim

pandas/_libs/lib.pyx

@@ -1839,27 +1839,5 @@ cdef class BlockPlacement:
         return self._as_slice
 
 
-cdef class _NDFrameIndexerBase:
-    '''
-    A base class for _NDFrameIndexer for fast instantiation and attribute
-    access.
-    '''
-    cdef public object obj, name, _ndim
-
-    def __init__(self, name, obj):
-        self.obj = obj
-        self.name = name
-        self._ndim = None
-
-    @property
-    def ndim(self):
-        # Delay `ndim` instantiation until required as reading it
-        # from `obj` isn't entirely cheap.
-        ndim = self._ndim
-        if ndim is None:
-            ndim = self._ndim = self.obj.ndim
-        return ndim
-
-
 include "reduce.pyx"
 include "inference.pyx"

pandas/core/generic.py

@@ -1,5 +1,6 @@
 # pylint: disable=W0231,E1101
 import collections
+import functools
 import warnings
 import operator
 import weakref
@@ -1841,10 +1842,8 @@ def to_latex(self, buf=None, columns=None, col_space=None, header=True,
     @classmethod
     def _create_indexer(cls, name, indexer):
         """Create an indexer like _name in the class."""
-        from functools import partial
-
         if getattr(cls, name, None) is None:
-            _indexer = partial(indexer, name)
+            _indexer = functools.partial(indexer, name)
             setattr(cls, name, property(_indexer, doc=indexer.__doc__))
 
     def get(self, key, default=None):

pandas/core/indexing.py

@@ -23,7 +23,7 @@
 from pandas.core.common import (is_bool_indexer, _asarray_tuplesafe,
                                 is_null_slice, is_full_slice,
                                 _values_from_object)
-from pandas._libs.lib import _NDFrameIndexerBase
+from pandas._libs.indexing import _NDFrameIndexerBase
 
 
 # the supported indexers

setup.py

@@ -335,6 +335,7 @@ class CheckSDist(sdist_class):
                  'pandas/_libs/index.pyx',
                  'pandas/_libs/algos.pyx',
                  'pandas/_libs/join.pyx',
+                 'pandas/_libs/indexing.pyx',
                  'pandas/_libs/interval.pyx',
                  'pandas/_libs/hashing.pyx',
                  'pandas/_libs/testing.pyx',
@@ -519,6 +520,7 @@ def pxd(name):
                    'depends': _pxi_dep['join']},
     '_libs.reshape': {'pyxfile': '_libs/reshape',
                       'depends': _pxi_dep['reshape']},
+    '_libs.indexing': {'pyxfile': '_libs/indexing'},
     '_libs.interval': {'pyxfile': '_libs/interval',
                        'pxdfiles': ['_libs/hashtable'],
                        'depends': _pxi_dep['interval']},