From 49392c63a243052c8013bef80d35202bb6d7c404 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Mon, 25 Sep 2017 01:21:06 -0700 Subject: [PATCH] bpo-27385: Clarify docstring for groupby() (#3738) --- Doc/library/itertools.rst | 2 +- Modules/itertoolsmodule.c | 5 +++-- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index 530c29dec4a..fa6c340bb7b 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -53,7 +53,7 @@ Iterator Arguments Results :func:`compress` data, selectors (d[0] if s[0]), (d[1] if s[1]), ... ``compress('ABCDEF', [1,0,1,0,1,1]) --> A C E F`` :func:`dropwhile` pred, seq seq[n], seq[n+1], starting when pred fails ``dropwhile(lambda x: x<5, [1,4,6,4,1]) --> 6 4 1`` :func:`filterfalse` pred, seq elements of seq where pred(elem) is false ``filterfalse(lambda x: x%2, range(10)) --> 0 2 4 6 8`` -:func:`groupby` iterable[, keyfunc] sub-iterators grouped by value of keyfunc(v) +:func:`groupby` iterable[, key] sub-iterators grouped by value of key(v) :func:`islice` seq, [start,] stop [, step] elements from seq[start:stop:step] ``islice('ABCDEFG', 2, None) --> C D E F G`` :func:`starmap` func, seq func(\*seq[0]), func(\*seq[1]), ... ``starmap(pow, [(2,5), (3,2), (10,3)]) --> 32 9 1000`` :func:`takewhile` pred, seq seq[0], seq[1], until pred fails ``takewhile(lambda x: x<5, [1,4,6,4,1]) --> 1 4`` diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c index 2ac5ab24ec8..cc9895a942d 100644 --- a/Modules/itertoolsmodule.c +++ b/Modules/itertoolsmodule.c @@ -176,8 +176,9 @@ static PyMethodDef groupby_methods[] = { }; PyDoc_STRVAR(groupby_doc, -"groupby(iterable[, keyfunc]) -> create an iterator which returns\n\ -(key, sub-iterator) grouped by each value of key(value).\n"); +"groupby(iterable, key=None) -> make an iterator that returns consecutive\n\ +keys and groups from the iterable. If the key function is not specified or\n\ +is None, the element itself is used for grouping.\n"); static PyTypeObject groupby_type = { PyVarObject_HEAD_INIT(NULL, 0)