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Talyahav17 wants to merge 7 commits into pandas-dev:main

from Talyahav17:doc/clarify-categorical-map

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DOC: clarify Series.map behavior for categorical dtype #62338

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DOC: clarify Series.map behavior for categorical dtype

Talyahav17 Sep 14, 2025

Talyahav17 Sep 14, 2025

DOC: address review — move categorical map note to Examples and trim ...

Talyahav17 Sep 16, 2025

Merge branch 'main' into doc/clarify-categorical-map

Talyahav17 Sep 18, 2025

DOC: fix doctest in categorical.map by removing SKIP markers

Talyahav17 Sep 21, 2025

FIX: remove whitespace from blank line in series.py

Talyahav17 Sep 21, 2025

Merge branch 'main' into doc/clarify-categorical-map

Talyahav17 Sep 21, 2025

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16 changes: 16 additions & 0 deletions pandas/core/arrays/categorical.py

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Original file line number	Diff line number	Diff line change
Expand Up		@@ -1585,6 +1585,22 @@ def map(

		>>> cat.map({"a": "first", "b": "second"}, na_action=None)
		Index(['first', 'second', nan], dtype='str')

	The mapping function is applied to categories, not to each value. It is
	therefore only called once per unique category, and the result reused for
	all occurrences:

	>>> cat = pd.Categorical(["a", "a", "b"])
	>>> calls = []
	>>> def f(x):
	... calls.append(x)
	... return x.upper()
	>>> result = cat.map(f)
	>>> result
	['A', 'A', 'B']
	Categories (2, str): ['A', 'B']
	>>> calls
	['a', 'b']
		"""
		assert callable(mapper) or is_dict_like(mapper)

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28 changes: 28 additions & 0 deletions pandas/core/series.py

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Original file line number	Diff line number	Diff line change
Expand Up		@@ -4419,6 +4419,34 @@ def map(
		2 NaN
		3 I am a rabbit
		dtype: object

	For categorical data, the function is only applied to the categories:

	>>> s = pd.Series(list("cabaa"))
	>>> s.map(print)
	c
	a
	b
	a
	a
	0 None
	1 None
	2 None
	3 None
	4 None
	dtype: object

	>>> s_cat = s.astype("category")
	>>> s_cat.map(print) # function called once per unique category
	a
	b
	c
	0 None
	1 None
	2 None
	3 None
	4 None
	dtype: object
		"""
		if func is None:
		if "arg" in kwargs:
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