On Tue, Mar 20, 2012 at 11:46 AM, Tom Diethe <tdie...@gmail.com> wrote:
> I'm writing a wrapper for sparse matrices (CSR format) and therefore
> need to store three vectors and 3 scalars:
>
> - data (float64 vector)
> - indices (int32 vector)
> - indptr (int32 vector)
>
> - nrows (int32 scalar)
> - ncols (int32 scalar)
> - nnz (int32 scalar)
>
> data and indices will always be the same length as each other (=nnz)
> but the indptr vector is much shorter.
>
> I've written routines that allow you to insert/update/delete rows or
> columns of the matrix by acting on these vectors only. However I'm
> struggling to work out the best pytables structure to store these,
> that allows me to append/insert/delete elements easily, and is
> efficient.
>
> I was using a Group with an EArray for each vector. This works ok but
> it seems like you are unable to delete items - is that correct?
>
> I also tried using a Group with a separate Table for each of the
> vectors (I could possibly just have two - one for data and indices and
> the other for indptr), but this seems to add a lot of overhead in
> manipulating the arrays.
>
> Is there something simple I'm missing?
>
Hi Tom,
It seems to me that what you want to be using is a Table, which supports a
lot of the functionality you desire, including removing rows (which EArrays
don't easily support)
http://pytables.github.com/usersguide/libref.html?highlight=remove#tables.Table.removeRows
.
Rather than having a Group of EArrays, have a table whose columns represent
what you were storing in the EArrays. You should take a look at the Tables
tutorials to see how to do this:
http://pytables.github.com/usersguide/tutorials.html
Be Well
Anthony
>
> Tom
>
>
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