[SciPy-user] Sparse matrices
David Grant
david at dwavesys.com
Wed Nov 10 16:08:13 EST 2004
Travis Oliphant wrote:
> Nils Wagner wrote:
>
>> Hi all,
>>
>> from scipy import *
>> A = sparse.dok_matrix()
>>
>> for i in range(3):
>> A[i,i] = 0.0+0.0j
>> # A[i,i] = 0.1+0.0j
>>
>> n,m = A.shape
>> print n,m
>> print A
>>
>>
>> n, m should be equal to 3, but this is only valid for non-zero entries.
>>
>> Am I missing something ?
>
>
> Entering a zero value into a sparse matrix causes no storage and
> therefore no shape changes. A remains an empty sparse matrix. What
> are you trying to do?
>
>
One thing that it is interesting. These sparse arrays are dynamically
allocated I assume? In the PySparse package, arrays are dynamically
allocated, but the shape must be set upon initialization. It looks like
you've made a more flexible package here.
More information about the SciPy-User
mailing list