notebook.community

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In [4]:

    
from scipy.sparse import *
from scipy import *
row = array([0,0,1,2,2,2])
col = array([0,2,2,0,1,2])
data = array([1,2,3,4,5,6])
A=csr_matrix( (data,(row,col)), shape=(3,3) )



In [7]:

    
print A.todense()
lumped = A.sum(1)









    



[[1 0 2]
 [0 0 3]
 [4 5 6]]



In [9]:

    
lumped.A









    Out[9]:





array([[ 3],
       [ 3],
       [15]])