scipy csr_matrix demo

csr_test.py

import numpy as np
from scipy.sparse import *
import pygraphviz as pgv
import random

a = np.array([[1,0,0,0],
              [5,2,0,0],
              [1,7,2,0],
              [0,0,0,4]])

a = csr_matrix(a)

a.data[1] = 0
print a.data
print a.indices

# Deleting a row is not possible without re arranging the the rest of indptr
# array
print a.indptr

# now the 2nd row contains a 0 entry
print a