Artificial creating of [Lists], is it possible? the best way...

[Grant Edwards]

On 2017-11-17, eth0 <ethernet.zero at gmail.com> wrote:
> On Fri, 17 Nov 2017 00:04:16 +0000 in comp.lang.python, MRAB said:
>>  On 2017-11-16 18:47, jakub.rajcok at gmail.com wrote:
>> > Hello, im working on school project, its deck game Sorry!
>> > I need to create specific lists:
>> > My idea is about to using for
>> > For i in range (n):
>> >         i=[]
>> > I know, that there is no possibility to make it from number, but
>> > i havent idea, how to reach my wants Li/L"i"/L(i), how to make
>> > possible for lists?
>> > 
>> > 
>>  If you want multiple lists, make a list of lists:
>> 
>>  my_lists = []
>> 
>>  for i in range(n):
>>       my_lists.append([])
>> 
>>  Then you can say my_lists[0], my_lists[1], etc.
>
> It'd be even shorter using a list comprehension:
>
> my_lists = [[] for i in range(n)]
>
> And _even shorter still_ just using the multiply operator:
>
> my_lists = [[]] * n

   $ python
   Python 2.7.14 (default, Nov  2 2017, 11:45:51) 
   [GCC 5.4.0] on linux2
   Type "help", "copyright", "credits" or "license" for more information.
   >>> x = [[] for i in 1,2,3,4]
   >>> x
   [[], [], [], []]
   >>> y = [[]] * 4
   >>> y
   [[], [], [], []]
   >>> x[0].append(1)
   >>> y[0].append(1)
   >>> x
   [[1], [], [], []]
   >>> y
   [[1], [1], [1], [1]]



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Grant Edwards               grant.b.edwards        Yow! Do I have a lifestyle
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