`scipy.sparse._dok:dok_array`

source: /scipy/sparse/_dok.py :562

Signature

   def     dok_array (    arg1    ,    shape    =  None   ,    dtype    =  None   ,    copy    =  False   ,  * ,     maxprint    =  None     )

Summary

Dictionary Of Keys based sparse array.

Extended Summary

This is an efficient structure for constructing sparse arrays incrementally.

This can be instantiated in several ways:

dok_array(D): where D is a 2-D ndarray
dok_array(S): with another sparse array or matrix S (equivalent to S.todok())
dok_array((M,N), [dtype]): create the array with initial shape (M,N) dtype is optional, defaulting to dtype='d'

Attributes

dtype : dtype: Data type of the array
shape : 2-tuple: Shape of the array
ndim : int: Number of dimensions (this is always 2)
nnz: Number of nonzero elements
size
T

Notes

Sparse arrays can be used in arithmetic operations: they support addition, subtraction, multiplication, division, and matrix power.

Allows for efficient O(1) access of individual elements.
Duplicates are not allowed.
Can be efficiently converted to a coo_array once constructed.

Examples

import numpy as np
from scipy.sparse import dok_array
S = dok_array((5, 5), dtype=np.float32)
for i in range(5):
    for j in range(5):
        S[i, j] = i + j    # Update element