# Is there a better way of doing this?

mattia gervaz at gmail.com
Sat Mar 7 10:12:07 CET 2009

```Il Sat, 07 Mar 2009 00:05:53 -0200, Gabriel Genellina ha scritto:

> En Fri, 06 Mar 2009 21:31:01 -0200, mattia <gervaz at gmail.com> escribió:
>
>> Thanks, I've found another solution here:
>> http://www.obitko.com/tutorials/
>> genetic-algorithms/selection.php
>> so here is my implementation:
>>
>>
>> def get_fap(fitness, population):
>>     fap = []
>>     total = 0
>>     for x in population:
>>         f = fitness(x)
>>         fap += [(f, x)]
>>         total += f
>>     return sorted(fap, reverse=True), total
>
> Imagine you're working with someone side by side. You write a note in a
> piece of paper, put it into an envelope, and hand it to your co-worker.
> He opens the envelope, throws it away, takes the note and files it
> inside a folder right at the end. And you do this over and over. What's
> wrong in this story?
>
> Please save our trees! Don't waste so many envelopes - that's just what
> this line does:
>
>           fap += [(f, x)]
>
> Environmentally friendly Pythoneers avoid using discardable intermediate
> envelopes:
>
>           fap.append((f, x))
>

>>> rw = [[2,4], [4,5,6],[5,5]]
>>> rw += [[1,1]]*2
>>> rw
[[2, 4], [4, 5, 6], [5, 5], [1, 1], [1, 1]]
>>> rw = [[2,4], [4,5,6],[5,5]]
>>> rw.append([1,1]*2)
>>> rw
[[2, 4], [4, 5, 6], [5, 5], [1, 1, 1, 1]]
>>> rw = [[2,4], [4,5,6],[5,5]]
>>> rw.append([[1,1]]*2)
>>> rw
[[2, 4], [4, 5, 6], [5, 5], [[1, 1], [1, 1]]]
>>>
How can I recicle in this way using append?

```