[Numpy-discussion] Having difficulty with Matrix.py
Blair Hall
b.hall at irl.cri.nz
Thu Jun 5 16:23:07 CDT 2003
I have been caught out writing a simple function
that manipulates the elements of a matrix.
I have distilled the problem into the code below.
I find that 'sum' works with a Numeric
array but fails with a Matrix. Am I doing something
wrong? If not, what should I do to patch it?
(I am working under Windows with Numpy 23.0)
Here is the code:
# 'a' is a two dimensional array. The
# function simply places the sum of
# the first column in a[0,0]
def sum(a):
N = a.shape[0]
sum = 0
for i in range(N):
sum += a[i,0]
# This is the criticial line
a[0,0] = sum
return a[0,0]
#------------------------
if(__name__ == '__main__'):
import Numeric
import Matrix
a = Numeric.ones( (9,1) )
print sum( a ) # Ok
print sum( Matrix.Matrix( a ) ) # Fails
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