list permutations and weired list.remove funtion

Remco Gerlich scarblac at pino.selwerd.nl
Tue May 15 09:47:40 CEST 2001


Tim Gahnström /Bladerman <tim at bladerman.com> wrote in comp.lang.python:
> Hi
> I am new to python and happende to use the function list.remov(elem) it sure
> is usufull but it rendered me som hours of extra work until I found out that
> it really dont return the list with the elemen removed.
> 
> [1,2,3].remove(2) == null
> instead of
> [1,2,3].remove(2) ==[1,3]
> 
> It seems like it would have been about no cost to let it work that way to?

It changes the list. If it also returned the list, a line like

newlist = l.remove(2)

would suggest that l was unchanged, but it is. So all these functions either
change the list or return the new one, but never both.

> Another question.
> Is there an easy way to get al permutations of a list?
> eg.
> perms=list.perm()

There's no builtin function for this. There was a thread about this a while
ago, search for "list permutations" in this group at
http://groups.google.com/advanced_groups_search .

-- 
Remco Gerlich



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