[SciPy-user] sparse+slice? (and hello!)

[Bram de Jong - MTG]

Hi,

Ed Schofield wrote:
> On 17/05/2006, at 9:19 AM, Bram de Jong - MTG wrote:
>>
>> * A simple question to start of with, is it correct to say that the
>> sparse matrices do not support slicing?
> 
> I've added some support for slicing in more recent SVN versions.   
> It's now possible to use csc[:, j], csr[i, :], or lil[i, :].  These  
> should be efficient operations.  But slicing along the 'non-native'  
> axes, with csc[i, :], csr[:, j], or lil[:, j] would be slower (and  
> more complex to write), and these raise an IndexError.

Oh, that's great news... Is this Python-only, or C code? Just to know if 
I will have to recompile. (Are there daily builds somewhere?)

Perhaps slicing along the non-native axes could be supported as well, 
even if it's really slow... A simple docstring with a message about the 
speed would solve the problem, while supplying the user with a "full 
set". For small matrices or really sparse ones it won't be much of a 
problem I guess (?).

>> * a not-so-simple question: is there any documentation, tutorial,
>> introduction, ... to the sparse matrices of scipy? It seems neither  
>> the
>> official (feebased) docs mention them, nor are the docstrings *that*
>> extensive.
> 
> There are also more docstrings in SVN HEAD.  No tutorial yet,  
> although we've had several requests recently.  I'll see what I can do  
> after I've submitted my thesis in a few weeks ...

Ok, that's great as well...

thanks for the rapid reply!


  - bram

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