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CLN: simplify CategoricalIndex internals #24343

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Dec 18, 2018
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CLN: simplify CategoricalIndex internals #24343

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55 changes: 15 additions & 40 deletions pandas/core/indexes/category.py
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Original file line number Diff line number Diff line change
Expand Up @@ -133,8 +133,7 @@ def __new__(cls, data=None, categories=None, ordered=None, dtype=None,

return cls._simple_new(data, name=name)

def _create_from_codes(self, codes, categories=None, ordered=None,
name=None):
def _create_from_codes(self, codes, dtype=None, name=None):
"""
*this is an internal non-public method*

Expand All @@ -143,23 +142,20 @@ def _create_from_codes(self, codes, categories=None, ordered=None,
Parameters
----------
codes : new codes
categories : optional categories, defaults to existing
ordered : optional ordered attribute, defaults to existing
dtype: CategoricalDtype, defaults to existing
name : optional name attribute, defaults to existing

Returns
-------
CategoricalIndex
"""

if categories is None:
categories = self.categories
if ordered is None:
ordered = self.ordered
if dtype is None:
dtype = self.dtype
if name is None:
name = self.name
cat = Categorical.from_codes(codes, categories=categories,
ordered=ordered)
cat = Categorical.from_codes(codes, categories=dtype.categories,
ordered=dtype.ordered)
return CategoricalIndex(cat, name=name)

@classmethod
Expand Down Expand Up @@ -201,12 +197,10 @@ def _create_categorical(cls, data, categories=None, ordered=None,
return data

@classmethod
def _simple_new(cls, values, name=None, categories=None, ordered=None,
dtype=None, **kwargs):
def _simple_new(cls, values, name=None, dtype=None, **kwargs):
result = object.__new__(cls)

values = cls._create_categorical(values, categories, ordered,
dtype=dtype)
values = cls._create_categorical(values, dtype=dtype)
result._data = values
result.name = name
for k, v in compat.iteritems(kwargs):
Expand All @@ -218,29 +212,11 @@ def _simple_new(cls, values, name=None, categories=None, ordered=None,
# --------------------------------------------------------------------

@Appender(_index_shared_docs['_shallow_copy'])
def _shallow_copy(self, values=None, categories=None, ordered=None,
dtype=None, **kwargs):
# categories and ordered can't be part of attributes,
# as these are properties
# we want to reuse self.dtype if possible, i.e. neither are
# overridden.
if dtype is not None and (categories is not None or
ordered is not None):
raise TypeError("Cannot specify both `dtype` and `categories` "
"or `ordered`")

if categories is None and ordered is None:
dtype = self.dtype if dtype is None else dtype
return super(CategoricalIndex, self)._shallow_copy(
values=values, dtype=dtype, **kwargs)
if categories is None:
categories = self.categories
if ordered is None:
ordered = self.ordered

def _shallow_copy(self, values=None, dtype=None, **kwargs):
if dtype is None:
dtype = self.dtype
return super(CategoricalIndex, self)._shallow_copy(
values=values, categories=categories,
ordered=ordered, **kwargs)
values=values, dtype=dtype, **kwargs)

def _is_dtype_compat(self, other):
"""
Expand Down Expand Up @@ -425,10 +401,9 @@ def unique(self, level=None):
if level is not None:
self._validate_index_level(level)
result = self.values.unique()
# CategoricalIndex._shallow_copy keeps original categories
# and ordered if not otherwise specified
return self._shallow_copy(result, categories=result.categories,
ordered=result.ordered)
# CategoricalIndex._shallow_copy keeps original dtype
# if not otherwise specified
return self._shallow_copy(result, dtype=result.dtype)

@Appender(Index.duplicated.__doc__)
def duplicated(self, keep='first'):
Expand Down