Creating a list with holes

[Roy Smith]

In article <mailman.4852.1388762356.18130.python-list at python.org>,
 Larry Martell <larry.martell at gmail.com> wrote:

> I think I know the answer is no, but is there any package that allows
> creating a list with holes in it? E.g. I'd want to do something like:
> 
> x[10] = 12
> x[20] = 30

Whenever you ask, "What data structure do I want", you need to be able 
to answer, "What operations do I want to perform?, and, "What 
constraints do I have on memory use?"

Why do you want holes?  Is the issue that you're storing sparse data and 
don't want to waste memory on unused keys?  If so, a dictionary should 
do you fine.

Do you need to be able to read the values back out in a specific order?  
You can still do that with a dictionary if you're willing to re-sort the 
keys; that's O(n log n) on the number of keys, but if n is small, it 
doesn't matter.