[Tutor] packing a list of lists

[vince spicer]

On Fri, Aug 28, 2009 at 9:18 AM, vince spicer <vinces1979 at gmail.com> wrote:

>
>
> On Fri, Aug 28, 2009 at 8:05 AM, kevin parks <kp8 at me.com> wrote:
>
>> Back to python after a long long layoff. So i am running into some
>> beginner's confusion...
>>
>> I am trying to plot a list of numbers in gnuplot.py. To do that I am
>> trying to pack the list with an index by iterating over the list so i can
>> get something like:
>>
>> foo = [12, 11, 9, 6, 2, 9, 3, 8, 12, 3, 5, 6]
>>
>> [ [1, 12], [2, 11], [3, 9], [4, 6], [5, 2], [6, 9], [7, 3], [8, 8] ... ]
>>
>> So that i have x, y pairs to plot. When i print in my func i get the right
>> thing, for each item (note scaffolding) yet when i reurn the whole list i
>> just get the last pair repeated over and over.
>>
>> I am not sure why this is.
>>
>>
>> def pack(in_seq):
>>        out_list=[]
>>        x = 1
>>        ll=[1, 1]
>>        for each in in_seq:
>>                ll[0] = x
>>                ll[1] = each
>>                out_list.append(ll)
>>                #print ll
>>                x = x + 1
>>        print out_list
>>
>>
>> # function declarations would go here
>> def test():
>>        """test function - say what this does here and skip a line
>>
>>        Keyword arguments:
>>        none
>>        """
>>
>>        print
>>        foo = minus(200)
>>        plot_me = pack(foo)
>>        #print foo
>>        print
>>        print plot_me
>>
>>
>> if __name__ == "__main__":
>>        test()
>>
>>
>> _______________________________________________
>> Tutor maillist  -  Tutor at python.org
>> http://mail.python.org/mailman/listinfo/tutor
>>
>
>
> Although I didn't test your code, I think what you are trying to accomplish
> can be done using enumerate cleaner
>
>
> def pack(foo):
>     out = []
>     for x,y in enumerate(foo, 1):
>         out.append((x,y))
>     return out
>
>
>
>
Or even cleaner with list comprehension

def pack(foo):
    return [x for x in enumerate(foo, 1)]
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