list item's position

[Steven Bethard]

Bill Mill wrote:
> 2 solutions:
> 
> In [98]: bars = ["str", "foobaz", "barbaz", "foobar"]
> 
> In [99]: for bar in bars:
>    ....:     if 'bar' in bar and 'baz' in bar:
>    ....:         print bar
>    ....:         print bars.index(bar)
>    ....:
> barbaz
> 2
> 
> In [100]: for i in range(len(bars)):
>    .....:     if 'bar' in bars[i] and 'baz' in bars[i]:
>    .....:         print bars[i]
>    .....:         print i
>    .....:
> barbaz
> 2
> 
> The first one is slow and pretty, the second one is fast and (a bit)
> ugly. I believe that you should avoid range(len(x)) when you can, but
> use it when you need to know the index of something without an
> additional x.index() call.

See Mark's post, if you "need to know the index of something" this is 
the perfect case for enumerate (assuming you have at least Python 2.3):

py> bars = ["str", "foobaz", "barbaz", "foobar"]
py> for i, bar in enumerate(bars):
...     if 'bar' in bar and 'baz' in bar:
...         print bar
...         print i
...
barbaz
2

The only time where I even consider using range(len(x)) is when I don't 
also need to look at the item -- which I find to be quite uncommon...

Steve