General computer language, syntax question.

Joel Goldstick joel.goldstick at gmail.com
Mon Feb 29 09:48:48 EST 2016


On Mon, Feb 29, 2016 at 9:39 AM, Mark Lawrence <breamoreboy at yahoo.co.uk>
wrote:

> On 29/02/2016 13:45, 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.
>>
>>
> 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
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>
>>> l = []
>>> l
[]
>>> if l:
...   print 'not empty'
...
>>>


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


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