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Replace map(None, *iterables) with zip(*iterables).

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Raymond Hettinger 2008-01-22 23:25:35 +00:00
parent 86def6cb2b
commit 1dfde1ddc0
9 changed files with 20 additions and 90 deletions
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32
Modules/itertoolsmodule.c
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@ -1490,31 +1490,6 @@ imap_traverse(imapobject *lz, visitproc visit, void *arg)
return 0;
}
/*
imap() is an iterator version of __builtins__.map() except that it does
not have the None fill-in feature. That was intentionally left out for
the following reasons:
1) Itertools are designed to be easily combined and chained together.
Having all tools stop with the shortest input is a unifying principle
that makes it easier to combine finite iterators (supplying data) with
infinite iterators like count() and repeat() (for supplying sequential
or constant arguments to a function).
2) In typical use cases for combining itertools, having one finite data
supplier run out before another is likely to be an error condition which
should not pass silently by automatically supplying None.
3) The use cases for automatic None fill-in are rare -- not many functions
do something useful when a parameter suddenly switches type and becomes
None.
4) If a need does arise, it can be met by __builtins__.map() or by
writing: chain(iterable, repeat(None)).
5) Similar toolsets in Haskell and SML do not have automatic None fill-in.
*/
static PyObject *
imap_next(imapobject *lz)
{
@ -1536,8 +1511,6 @@ imap_next(imapobject *lz)
}
PyTuple_SET_ITEM(argtuple, i, val);
}
if (lz->func == Py_None)
return argtuple;
result = PyObject_Call(lz->func, argtuple, NULL);
Py_DECREF(argtuple);
return result;
@ -1547,10 +1520,7 @@ PyDoc_STRVAR(imap_doc,
"imap(func, *iterables) --> imap object\n\
\n\
Make an iterator that computes the function using arguments from\n\
each of the iterables. Like map() except that it returns\n\
an iterator instead of a list and that it stops when the shortest\n\
iterable is exhausted instead of filling in None for shorter\n\
iterables.");
each of the iterables. Stops when the shortest iterable is exhausted.");
static PyTypeObject imap_type = {
PyVarObject_HEAD_INIT(NULL, 0)