Michael Rauh wrote at Fri, 05 Jul 2002 08:39:42 +0200:
> hi,
>
> say i have an unsorted (large) list of, e.g., 0's and 1's:
>
> @list = (0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, ...)
>
> i now want to remove all the zeros, using the fastest way possible. how would U do
>that?
When it is so important to use to _fastest_ way,
then you should take C or assembler.
>
> i thought of sorting the zeros the left (or right) and then shift (or pop) all
>zeros. or perhaps
> to first find the offset and then do a single splice.
>
> but perhaps there's another way? performance is most important here. suggestions
>welcome.
A very quick perl method is to do exactly what you had written.
Remove all zeros == take everything what's not a zero
and that's the exact behaviour of the grep function:
my @removed_zeros_list = grep $_, @list;
# Linguistic view:
# the new list consists of all sensfull elements from the old list
(O.K. that removes every false value from the list -
if there are also '' or undefs or similar that shouldn't be removed,
you need something like
grep {$_ != 0}, @list;)
Best Wishes,
Janek
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