On Wed, 27 Apr 2011 17:42:30 -0700, Rusty Scalf wrote:
> Greetings,
> I am just now learning python and am trying to use the index function
> with variables.
>
> list1 = ['pig', 'horse', 'moose']
> list2 = ['62327', '49123', '79115']
> a = list2[list1.index('horse')]
> print a
> >49123
>
> -works fine. But
>
> list1 = ['pig', 'horse', 'moose']
> list2 = ['62327', '49123', '79115']
> n = 2
> s2 = "list" + `n`
> a = s2[list1.index('horse')]
> print a
>
> -does not work
Define "does not work".
What do you expect to happen, and what happens instead? When I try it,
index works perfectly. You can see that most clearly by extracting out
the call to index without all the other noise surrounding it.
>>> list1.index('horse')
1
Works fine.
Whatever your problem is, it has *nothing* to do with index. You could
remove the call to index completely:
>>> a = s2[1]
>>> print a
i
and get the same result.
If you print s2, you will see your problem:
>>> print s2 # do you expect it to be ['62327', '49123', '79115'] ?
list2
s2 is a string that happens to be the same as the name of the variable
list2. That's all.
> I'd like to use the index function in a loop updating the file names by
> adding a number to that name with each cycle. But can't get to first
> base.
Don't do it that way. Instead of:
filename1 = 'foo.txt'
filename2 = 'spam.doc'
filename3 = 'image.jpg'
Keep a list of file names:
filenames = ['foo.txt', 'spam.doc', 'image.jpg']
and work with that.
--
Steven
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