manipulate string

[David C. Fox]

>     import string
>     a='0123456789'
>     l=list(a[::2])
>     b=string.join(l,' - ')
>     print b

Chris wrote:

> It is me again.
> Unfortunately it doesn't work. Python doesn't accept [::2]
> TypeError: sequence index must be integer
> I use Python Release 2.2.3.
> Any ideas?
> 
> -Tom
> 

Yeah, the x[::i] notation for strings and lists only works in 2.3.

A couple of alternatives to l = list(a[::2]) which work in 2.2 are:

l = []
for i in range( (len(a) + 1) // 2):
   l.append(a[2*i])

or more compactly

l=[a[2*i] for i in range((len(a)+1)//2)]

or

l = [a[i] for i in range(len(a)) if 2*(i//2) == i]

David