Suggestion for impriving list comprehensions
bellman at lysator.liu.se
Fri Jul 27 00:37:20 CEST 2001
Guido van Rossum <guido at python.org> wrote:
> paul at svensson.org (Paul Svensson) writes:
>> [x for x in fib() while x < 50]
> Neat, but maybe not general enough. How do you request the first N?
How about one of these:
l = 
for i,v in zip(range(N), fib()):
l = ; g = fib()
for i in range(N):
or my personal favourite
map(lambda x,g=fib(): g.next(), range(N))
Not *every* list needs to be generated using list comprehension,
you know. :-) (My personal preferens is that every list should
be generated using map(), filter() or reduce(). :-)
> And fuzzy: does this include or exclude the first x >= 50?
Exclude. Definitely exclude.
> How about a library of functions for iterator algebra? E.g.
> def first(n, sq):
> it = iter(sq)
> for i in range(n): yield it.next()
> def lessthan(n, sq):
> for x in sq:
> if x >= n: break
> yield x
Could be usable, but please not in the builtin namespace. I'm
already starting to feel that the __builtin__ module is a bit
crowded. Or, well, perhaps not *crowded*, but rather that it is
somewhat a mish-mash of functions that no-one had the energy to
find the proper module for.
Thomas Bellman, Lysator Computer Club, Linköping University, Sweden
"Adde parvum parvo magnus acervus erit" ! bellman @ lysator.liu.se
(From The Mythical Man-Month) ! Make Love -- Nicht Wahr!
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