[Tutor] Finding uniq. in lists

[Daniel Yoo]

On Thu, 10 May 2001, Remco Gerlich wrote:

> On  0, steve <lonetwin@yahoo.com> wrote:
> > Hi all ye good people,
> >  Ques: Is there a nice ( read good+clean+efficient ) way to do this:
> > I have a list p = ['foo', 'bar', 'foo-bar', 'foo', 'foo-bar' ]
> > I want the list to contain only single instances of elements, ie:I want to 
> > filter out all the duplicate entries. This is the first thing that came to my 
> > mind :
> > 	q = [ p[i] for i in range(len(p)) if p[i] not in p[(i+1):] ]
> >  Prob. is I do not like it !! :) ...so either give me a better solu. or 
> > convince me that the solu. I have is not bad :)
> That will be too slow. Use a dictionary, it's the fastest way:
> 
> def uniq(q):
>    dict = {}
>    for s in q:
>       dict[s] = 1
>    return dict.keys()


Here's a hint of an alternative method.  If you have the list

    p = ['foo', 'bar', 'foo-bar', 'foo', 'foo-bar' ]

would your problem be easier if you rearranged the elements like this?

    p_arranged = ['bar', 'foo', 'foo', 'foo-bar', 'foo-bar']