Re: [Matplotlib-users] python question from matlab user

[Daπid <dav...@gm...>]

On Sunday, September 9, 2012, Eric Firing wrote:

> Regarding the need to pre-allocate: yes, matlab is slicker in this
> regard, and every now and then there is discussion about implementing
> equivalent behavior in numpy, or in an add-on module.
>

Technically, you don´t have to preallocate the memory, but every time you
expand your array, the whole of it will be copied to a new contiguous piece
of memory. This works, but it can be slow if you do it many times, or you
are handling big data.

Using a Python list is not much more flexible, but you could use carrays
(for chunked arrays), that are structures NumPyArrays-compatible (AFAIK)
that are stored non contiguosly in memory. Adding data only needs to move
one of those small pieces, instead of the whole array.