Drew a écrit :
>>What is your actual usecase?
>>
>>diez
>
>
> The issue is that I don't know how long the list will eventually be.
How is this an issue ? Python's lists are not fixed-sized arrays.
> Essentially I'm trying to use a 2D list to hold lines that I will
> eventually print to the screen.
>
> Blank elements in the list will be
> printed as spaces. I suppose every time I add an element, I could find
> the difference between the size of the list and the desired index and
> fill in the range between with " " values,
Yes. But note that [1,2,3,' ',' ',4]
is not the same thing as [1,2,3,,,4] (which is not valid Python FWIW).
> however I just wanted to
> see if there was a more natural way in the language.
I'm not sure I get it. Do you mean you're trying to use a list of lists
as a representation of a 2D matrix (IOW, a bitmap) ? Something like
bpm = [
['X',' ',' ',' ','X'],
[' ','X',' ','X',' '],
[' ',' ','X',' ',' '],
[' ','X',' ','X',' '],
['X',' ',' ',' ','X'],
]
If so, using dicts can be somewhat simpler and less memory-consuming:
d = {1:1, 2:2, 3:3}
d[10] = 4
for i in range(1, max(d.keys())+1):
print d.get(i, ' ')
That is, instead of storing useless spaces for "blank cells" and having
to do math to compute how many of them you have to insert/delete, you
just place stuff at desired indices, and 'fill in' spaces when printing
out to screen.
HTH
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