Any way to use a range as a key in a dictionary?
pavlovevidence at gmail.com
Sat Mar 28 02:11:56 CET 2009
On Mar 27, 1:06 pm, Duncan Booth <duncan.bo... at invalid.invalid> wrote:
> Carl Banks <pavlovevide... at gmail.com> wrote:
> > On Mar 27, 11:20 am, Paul Rubin <http://phr...@NOSPAM.invalid> wrote:
> >> Carl Banks <pavlovevide... at gmail.com> writes:
> >> > > if x in theDict:
> >> > > print x, v
> >> > Where does v come from?
> >> Oops, pasted from original. Meant of course "print x, theDict[x]".
> > You have look up x twice with that code, whereas you wouldn't have to
> > with this:
> > v = theDict.get(x)
> > if v is not None:
> > print x, v
> Note that while you only lookup x in the dict once your code does still
> involve two dict lookups: once to lookup the get method and once to lookup
> x. It also involves creating a new bound method object so if performance is
> a concern you'll find that either the 'if x in theDict: ...' or the
> try...except are likely to be faster.
Not necessarily: if the hash calculation for x is expensive enough the
get version would still be faster. If all you're doing is looking up
strings or ints (as the OP is doing) it's hardly going to matter
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