How to access sparse matrix elements?

Question

type(A)

A.shape
(8529, 60877)
print A[0,:]
  (0, 25)   1.0
  (0, 7422) 1.0
  (0, 26062)    1.0
  (0, 31804)    1.0
  (0, 41         


        

Answer 1

I fully acknowledge all the other given answers. This is simply a different approach.

To demonstrate this example I am creating a new sparse matrix:

from scipy.sparse.csc import csc_matrix
a = csc_matrix([[1, 0, 0, 0], [0, 0, 10, 11], [0, 0, 0, 99]])
print(a)

Output:

(0, 0)  1
(1, 2)  10
(1, 3)  11
(2, 3)  99

To access this easily, like the way we access a list, I converted it into a list.

temp_list = []
for i in a:
    temp_list.append(list(i.A[0]))

print(temp_list)

Output:

[[1, 0, 0, 0], [0, 0, 10, 11], [0, 0, 0, 99]]

This might look stupid, since I am creating a sparse matrix and converting it back, but there are some functions like TfidfVectorizer and others that return a sparse matrix as output and handling them can be tricky. This is one way to extract data out of a sparse matrix.