any() and all() Was: Pre-PEP: Dictionary accumulator methods
vze4rx4y at verizon.net
Sat Mar 19 10:31:17 CET 2005
> Actually I was just looking at Python 2.5 docs since you mentioned this.
> It says min() and max() will gain a key function parameter, and sort()
> gained one in Python 2.4 (news to me).
It also appears in itertools.groupby() and, for Py2.5, in heapq.nsmallest() and
> And they do indeed default to the identity in all 3 cases, so this seems
> very inconsistent. If one of them has it, and sort gained the argument even
> in Python 2.4 with generator expressions, then they all should have it.
> > any(x >= 42 for x in data)
> Not to belabor the point, but in the example on that page, max(L, key=len)
> could be written max(len(x) for x in L).
Think about it. A key= function is quite a different thing. It provides a
*temporary* comparison key while retaining the original value. IOW, your
re-write is incorrect:
>>> L = ['the', 'quick', 'brownish', 'toad']
>>> max(L, key=len)
>>> max(len(x) for x in L)
Remain calm. Keep the faith. Guido's design works fine.
No important use cases were left unserved by any() and all().
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