On May 27, 6:43 pm, "Ian Kelly" <[EMAIL PROTECTED]> wrote:
> On Tue, May 20, 2008 at 11:19 AM, John Salerno <[EMAIL PROTECTED]> wrote:
> > "Diez B. Roggisch" <[EMAIL PROTECTED]> wrote in message
> >news:[EMAIL PROTECTED]
> >> After being corrected about missing the construction of a None-containing
> >> list, one needs of course to think about the waste of resources, as a
> >> possible result-list is created in any case.
>
> > Yeah, I was already aware of the list of Nones, which is why I asked. Simply
> > typing the list comprehension without an assignment just *looked* wrong,
> > too.
>
> It sounds like the wasteful list creation is the biggest objection to
> using a list comprehension. I'm curious what people think of this
> alternative, which avoids populating the list by using a generator
> expression instead (apart from the fact that this is still quadratic,
> which I'm aware of).
>
> def compress(s):
> new = []
> filter(None, (new.append(c) for c in s if c not in new))
> return ''.join(new)
It could be shorter:
def compress(s):
new = []
return filter(None, (new.append(c) for c in s if c not in new)) or
''.join(new)
:-)
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