In [1]:

    

from scipy.sparse import csr_matrix, coo_matrix, lil_matrix


    

In [2]:

    

lil = lil_matrix((3, 3), dtype=int)
print(lil.toarray())


    

    




[[0 0 0]
 [0 0 0]
 [0 0 0]]

In [3]:

    

lil[1, 0] = 10
lil[2, 2] = 30


    

In [4]:

    

print(lil)


    

    




  (1, 0)	10
  (2, 2)	30

In [5]:

    

print(lil.toarray())


    

    




[[ 0  0  0]
 [10  0  0]
 [ 0  0 30]]

In [6]:

    

lil[2, 2] = 0


    

In [7]:

    

print(lil)


    

    




  (1, 0)	10

In [8]:

    

print(lil.toarray())


    

    




[[ 0  0  0]
 [10  0  0]
 [ 0  0  0]]

In [9]:

    

csr = csr_matrix((3, 3), dtype=int)
print(csr.toarray())


    

    




[[0 0 0]
 [0 0 0]
 [0 0 0]]

In [10]:

    

# csr[1, 0] = 10
# SparseEfficiencyWarning: Changing the sparsity structure of a csr_matrix is expensive. lil_matrix is more efficient.


    

In [11]:

    

coo = coo_matrix((3, 3), dtype=int)


    

In [12]:

    

# coo[1, 0] = 10
# TypeError: 'coo_matrix' object does not support item assignment