Miki,
That sounds quite a bit like:
from itertools import imap, izip
argmax = lambda funct, items: max(izip(imap(funct, items), items))
argmin = lambda funct, items: min(izip(imap(funct, items), items))
Which breaks ties on vals using a comparison with items (I don't know if
this is desireable to you).
Running a quick test on large sequences (range(100000)) with a
relatively simple function (lambda a:a*a) produces the following timings
on my machine (best of 7):
argmax: 5.953 seconds (with std. dev. of .01455 seconds)
izipimap: 5.844 seconds (with std. dev. of .03009 seconds)
zipmap: 6.407 seconds (with std. dev. of .072356 seconds)
Seems to be a small win for itertools, a close second for your original argmax,
and a harrowing loss for map and zip on large sequences.
I don't know how anyone would feel about adding it to the standard
library,
- Josiah
> Do you think there is a place for an "argmax" function (which I use a lot)
> in the standard library?
>
> I'm thinking in the lines of:
>
> def argmax(items, func, cmp=cmp):
> '''argmax(items, func) -> max_item, max_value'''
> it = iter(items)
> # Initial values
> try:
> item = it.next()
> except StopIteration:
> raise ValueError("can't run over empty sequence")
> val = func(item)
>
> for i in it:
> v = func(i)
> if cmp(v, val) == 1:
> item = i
> val = v
> return item, val
>
> def argmin(items, func, cmp=cmp):
> '''argmin(items, func) -> min_item, min_value'''
> return argmax(items, func, lambda x,y : -cmp(x,y))
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