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From: Mark Lawrence <breamoreboy@yahoo.co.uk>
Newsgroups: comp.lang.python
Subject: Re: General computer language, syntax question.
Date: Mon, 29 Feb 2016 14:39:49 +0000
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On 29/02/2016 13:45, jonas.thornvall@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.
>

Please see 
https://docs.python.org/3/library/stdtypes.html#truth-value-testing

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence