python中構建稀疏矩陣

python中構建稀疏矩陣主要基於scipy的coo_matrix, csr_matrix。csr_matrix存儲密度更大，但是不容易手工構建。一般先基於coo_matrix構建稀疏矩陣，然後通過tocsr()轉換成csr_matrix

>>> import numpy as np
>>> row = np.array([0, 3, 1, 0])
>>> col = np.array([0, 3, 1, 2])
>>> data = np.array([4,5,7,8])
>>> import scipy.sparse
>>> from scipy.sparse import coo_matrix, csr_matrix
>>> d1 = coo_matrix((data, (row, col)))
>>> d1.toarray()
array([[4, 0, 8, 0],
       [0, 7, 0, 0],
       [0, 0, 0, 0],
       [0, 0, 0, 5]])
>>>