[Tutor] for loop results into list

[Andre Engels]

On Sun, Sep 5, 2010 at 8:51 PM, Micheal Beatty <mikelbt at gmail.com> wrote:
>  On 09/05/2010 01:26 PM, Evert Rol wrote:
>>>
>>> Hello all,
>>>
>>> I'm having a little problem figuring out how to accomplish this simple
>>> task. I'd like to take a list of 6 numbers and add every permutation of
>>> those numbers in groups of four. For example for 1, 2, 3, 4, 5, 6 add 1 + 1
>>> + 1 +1 then 1 + 1 + 1 +2 etc. until reaching 6 + 6 + 6 + 6. Using a for
>>> loop, that was the easy part, now I'd like to take the results and count the
>>> number of times each number occurs.
>>> My problem occurs when I try to create a list from the results of the for
>>> loop, it puts each individual number into its own list. I've looked
>>> everywhere for the solution to this and can find nothing to help.
>>>
>>> Any suggestions would be much appreciated
>>
>> If you had some code, that would be very helpful. Now it's a bit of
>> guesswork what exactly you have (code tends to be clearer than a full
>> paragraph or two of text).
>> At least, I currently don't understand what your problem is (or what your
>> for-loop involves).
>> Eg, are you looping and calling a function recursively, do you have four
>> nested loops (or nested list comprehensions)? Or some other convenient loop
>> to step through all combinations?
>>
>> Anway, if you have a recent Python version (2.7 or 3.1), the itertools
>> module provides a handy utiity:
>> http://docs.python.org/py3k/library/itertools.html#itertools.combinations_with_replacement
>> Eg,
>>
>>>>> map(sum, combinations_with_replacement(range(1,7), 4))
>>
>> [4, 5, 6, 7, 8, 9, 6, 7, 8, 9, 10, 8, 9, 10, 11, 10, 11, 12, 12, 13, 14,
>> 7, 8, 9, 10, 11, 9, 10, 11, 12, 11, 12, 13, 13, 14, 15, 10, 11, 12, 13, 12,
>> 13, 14, 14, 15, 16, 13, 14, 15, 15, 16, 17, 16, 17, 18, 19, 8, 9, 10, 11,
>> 12, 10, 11, 12, 13, 12, 13, 14, 14, 15, 16, 11, 12, 13, 14, 13, 14, 15, 15,
>> 16, 17, 14, 15, 16, 16, 17, 18, 17, 18, 19, 20, 12, 13, 14, 15, 14, 15, 16,
>> 16, 17, 18, 15, 16, 17, 17, 18, 19, 18, 19, 20, 21, 16, 17, 18, 18, 19, 20,
>> 19, 20, 21, 22, 20, 21, 22, 23, 24]
>>
>> seems to do what you want.
>>
>> But, I'd still say to adopt your own code first, and when you've learned
>> from that, just use the one-liner above. You're most welcome to ask your
>> question, best done in combination with code, actual output and expected
>> output. Then we can point you in the right direction.
>>
>> Cheers,
>>
>>   Evert
>>
> Thanks Evert, here is the code.
>
>
> fourdsix = [1, 2, 3, 4, 5, 6]
> for i in fourdsix:
>    for j in fourdsix:
>        for k in fourdsix:
>            for l in fourdsix:
>                fourdsix_result = [i, j, k, l]
>                attribs = sum(fourdsix_result) - min(fourdsix_result)
>                print attribs
>
> This gives me the proper results, now it's just a matter of getting it into
> a list so I can further work with the data.
> I've tried the following
> attrib_list = [attribs]
>
> and
> attrib_list = []
> attrib_list.append(attribs)
> print attrib_list
>
> but these both only create a list of the last number.

Put the attrib_list = [] before the beginning of the outer loop, and
it should work as intended. Now you are creating a new list each time,
which is not what you want.



-- 
André Engels, andreengels at gmail.com