在Python中使用SciPy创建稀疏矩阵

Question

I am trying to create a sparse matrix by reading the documentation.

So, according to the documentation ( https://docs.scipy.org/doc/scipy/reference/generated/scipy.sparse.csr_matrix.html ):

When I try:

csr_matrix((data = np.array([1, 1, 1, 1, 1, 1]), indices = np.array(2, 3, 4, 5, 7, 7), indptr = np.array([0, 1, 2, 3, 2, 1])))

I get an exception:

File "", line 1 csr_matrix((data = np.array([1, 1, 1, 1, 1, 1]), indices = np.array(2, 3, 4, 5, 7, 7), indptr = np.array([0, 1, 2, 3, 2, 1]))) ^ SyntaxError: invalid syntax

When I try:

csr_matrix((np.array([1, 1, 1, 1, 1, 1]), np.array(2, 3, 4, 5, 7, 7), np.array([0, 1, 2, 3, 2, 1])))

again an error message results:

ValueError: only 2 non-keyword arguments accepted

My intention here is to create a matrix which has ones in the columns with indexes
2, 3, 4, 5, 7, 7
where the corresponding rows have indexes
0, 1, 2, 3, 2, 1

(ie, (0, 2) , (1, 3) , (2, 4) etc).

Answer 1

You should be all set with

from scipy.sparse import csr_matrix
import numpy as np

my_csr = csr_matrix((np.array([1,1,1,1,1,1]), (np.array([0, 1, 2, 3, 2, 1]), np.array([2, 3, 4, 5, 7, 7]))), shape = (8,8))

Note that you need to specify the shape of the matrix (here I set the matrix to be a square 8x8 matrix via the parameter shape ). Note also the order of the arrays and the use of round brackets!

You can verify that this is satisfactory by converting to a dense format:

my_csr.toarray()