Am Montag, den 18.07.2005, 00:53 +0200 schrieb Max Noel: > On Jul 17, 2005, at 20:18, Bill Campbell wrote: > > > Is there any significant performance difference between the > > tests, ``key in dictionary'' and ``dictionary.has_key(key)''? > > I would prefer using the ``key in'' because it's a bit easier to > > type, and can also be used with lists in addition to dictionaries. > > While we're on that topic, is there a particular reason why > 'in', in a dict context, searches the keys instead of doing the > logical thing and searching the values?
Well, sorry I consider key in dict to be more natural than value in dict. Actually, there are implementation aspects: key in dict is a hash lookup. value in dict is a slow iteration over an unsorted "list". The only way to have a quick value lookup in a dict is keeping a shadow dictionary with inverted keys and values. (And if it's not a bijective relationship you probably need value -> list of keys) Andreas
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