General computer language, syntax question.

Joel Goldstick joel.goldstick at gmail.com
Mon Feb 29 08:55:19 EST 2016


On Mon, Feb 29, 2016 at 8:45 AM, <jonas.thornvall at gmail.com> wrote:

> I have a problem programming uniform networks, "x nodes with y links" that
> turn out to be really hairy to solve for me and i feel i really lack the
> programming features
>
> "Actually i program in javascript" but the problem seem general for all
> programming languages including Pyhton.
>
> For a beautiful solution it would require "If in list/array return
> boolean" "If not in list/array return boolean".
>
> But there is no such feature Python nor Javascript, so instead i set
> boolean value "inlist" to false and loop thru, to see if it is already in
> list. If not it is added to list.
>
> So if the current node i generate links for is x and i try to generate a
> link to  node z, and z's links exhausted i will add it to exhausted list.
>
> And if there is node-x exhausted entries in list, well then script should
> break because it will lock into a cycle. The cyclic lockup is due to only a
> subset of the networks on the form (links*deep)+1=nodes is possible.
>
> So what i need is to know howto write "if list/array ***empty*** do
> {something}"
>
> I sure know howto check if an array have 1 element 2,3,4 but how do you
> check for empty.
>
> I think it is crazy that you can not do general comparissons of the type
> If in list/array
> If not in list/array
>
> But it is even more crazy that you can not check if list/array is empty,
> that is just madness.
> --
> https://mail.python.org/mailman/listinfo/python-list
>

>>> l = [1,2,3,4]
>>> if 1 in l:
...   print 1
...
1
>>> if 6 in l:
...   print 1
...
>>>
>>> l = []
>>> if len(l) == 0:
...   print 'empty'
...
empty


-- 
Joel Goldstick
http://joelgoldstick.com/ <http://joelgoldstick.com/stats/birthdays>
http://cc-baseballstats.info/


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