Removal of element from list while traversing causes the next element to be skipped

Neil Cerutti mr.cerutti at gmail.com
Wed Jan 30 14:45:03 CET 2008


On 30 Jan 2008 05:20:49 -0800, Paul Rubin
<"http://phr.cx"@nospam.invalid> wrote:
> "Neil Cerutti" <mr.cerutti at gmail.com> writes:
> > Or one can put on his bellbottoms, horn-rimmed glasses, and wear a mullet:
> >
> > i = 0
> > while i < len(a):
> >   if a[i] == 99:
> >     del a[i]
> >   else:
> >     i += 1
>
> Quadratic time!! Yowch!!  Back to the future:
>
> def rocket_science(xs):
>    for x in xs:
>       if x != 99:
>          yield x
>
> a[:] = list(rocket_science(a))

Heh.

<lamely>It's probably a fairly peppy quadratic operation though.</lamely>

Besides, wherever will I find plutonium or a bolt of lightning?

-- 
Neil Cerutti <mr.cerutti+python at gmail.com>



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