manipulate string

[David C. Fox]

David C. Fox wrote:

>>     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
> 

or

l = [a[i] for i in range(0, len(a), 2)]

David