pysparse-users

[Pysparse-users] Reshape Matrix

[<mv...@uv...>]

Hi,

I was wondering if there is an easy way to extend or reshape a matrix.

For example...
If I had a vector of length 10000 (shape=(1,10000)), then wanted to insert
a new element at position 11000 without creating an entirely new vector to
store it.

I've looked at the Docs, and messed around with the package but was unable
to find a simple way to do this.  Any tips would be appreaciated.

Thanks,
Matt

Re: [Pysparse-users] Reshape Matrix

[Dominique O. <dom...@gm...>]

On Sat, Oct 24, 2009 at 5:02 PM,  <mv...@uv...> wrote:
> Hi,
>
> I was wondering if there is an easy way to extend or reshape a matrix.
>
> For example...
> If I had a vector of length 10000 (shape=(1,10000)), then wanted to insert
> a new element at position 11000 without creating an entirely new vector to
> store it.
>
> I've looked at the Docs, and messed around with the package but was unable
> to find a simple way to do this.  Any tips would be appreaciated.
>
> Thanks,
> Matt

Hi Matt,

Currently there is no provision for reshaping, clipping or expanding
matrices in PySparse. I can only imagine doing this efficiently on
matrices in linked-list format. There are essentially two ways to
implement it: by adding methods at C level in ll_mat.c, or by
expanding/subclassing the high-level PysparseMatrix class. If you
decide to have a stab at it, I suggest the second avenue first,
although I am not sure at this point that it is doable without getting
your hands dirty in the C code.

Are you in a situation where you don't know your problem size beforehand?

-- 
Dominique

Re: [Pysparse-users] Reshape Matrix

[<mv...@uv...>]

> On Sat, Oct 24, 2009 at 5:02 PM,  <mv...@uv...> wrote:
>> Hi,
>>
>> I was wondering if there is an easy way to extend or reshape a matrix.
>>
>> For example...
>> If I had a vector of length 10000 (shape=(1,10000)), then wanted to
>> insert
>> a new element at position 11000 without creating an entirely new vector
>> to
>> store it.
>>
>> I've looked at the Docs, and messed around with the package but was
>> unable
>> to find a simple way to do this.  Any tips would be appreaciated.
>>
>> Thanks,
>> Matt
>
> Hi Matt,
>
> Currently there is no provision for reshaping, clipping or expanding
> matrices in PySparse. I can only imagine doing this efficiently on
> matrices in linked-list format. There are essentially two ways to
> implement it: by adding methods at C level in ll_mat.c, or by
> expanding/subclassing the high-level PysparseMatrix class. If you
> decide to have a stab at it, I suggest the second avenue first,
> although I am not sure at this point that it is doable without getting
> your hands dirty in the C code.
>
> Are you in a situation where you don't know your problem size beforehand?
>
> --
> Dominique
>
>

Hey Dominique,

Thanks for the quick reply.  No, for most of this application I will not
know the size of the problem before hand.
I think I can still do it, it will just require a change in my thinking
and program flow.

If I do endup needing this feature(or it just makes it way simpler) I'll
gladly hack away at the c code to make it work and share any changes.


Thanks,
MV