[SciPy-user] ValueError: need more than 1 value to unpack

Nils Wagner nwagner at mecha.uni-stuttgart.de
Thu Mar 16 05:56:23 CST 2006


Ed Schofield wrote:
> Nils Wagner wrote:
>   
>> Is this a bug ?
>>
>>     A_csc = csc_matrix((3,3),Complex128)
>>   File "/usr/lib64/python2.4/site-packages/scipy/sparse/sparse.py", line
>> 521, in __init__
>>     (M, N) = dims
>> ValueError: need more than 1 value to unpack
>>   
>>     
>
> This works fine for me:
>
>   
>>>> from scipy import sparse as s
>>>> import numpy
>>>> A_csc = s.csc_matrix((3,3), numpy.complex128)
>>>>         
>
> Try with a lowercase 'complex128'.  I think the uppercase dtype names
> are deprecated, but also _different_ to the lowercase dtype names, so
> Complex128 would be equivalent to complex256 -- that is, the real and
> imaginary components are both 128-bit floats.  Complex128, with
> uppercase 'C', is not even defined on my 32-bit machine...
>
>   
On a 32bit system

    A_csc = s.csc_matrix((3,3),Complex128)
NameError: name 'Complex128' is not defined

If I use a lowercase dtype name
A_csc = s.csc_matrix((3,3),complex128)
for i in arange(0,3):

    A_csr[i,i] = 1.0+2j
    A_csc[i,i] = 1.0+2j

>>> A_csc
<3x3 sparse matrix of type '<type 'float64scalar'>'
        with 3 stored elements (space for 100)
        in Compressed Sparse Column format>

Note that the imaginary part is missing !

>>> print A_csc
  (0, 0)        1.0
  (1, 1)        1.0
  (2, 2)        1.0


Nils

> But it looks like a bug anyway.  Robert C., do you have a 64-bit machine
> to investigate this?
>
> -- Ed
>
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