Sparse matrix with DIAgonal storage
This can be instantiated in several ways: dia_matrix(D) with a dense matrix
dia_matrix(S) with another sparse matrix S (equivalent to S.todia())
dia_matrix((M, N), dtype) to construct an empty matrix with shape (M, N), dtype is optional, defaulting to dtype='d'.
dia_matrix((data, offsets), shape=(M, N)) where the ``datak,:`` stores the diagonal entries for diagonal ``offsetsk`` (See example below)
Attributes ---------- dtype : dtype Data type of the matrix shape : 2-tuple Shape of the matrix ndim : int Number of dimensions (this is always 2) nnz Number of stored values, including explicit zeros data DIA format data array of the matrix offsets DIA format offset array of the matrix
Notes -----
Sparse matrices can be used in arithmetic operations: they support addition, subtraction, multiplication, division, and matrix power.
Examples --------
>>> import numpy as np >>> from scipy.sparse import dia_matrix >>> dia_matrix((3, 4), dtype=np.int8).toarray() array([0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], dtype=int8)
>>> data = np.array([1, 2, 3, 4]).repeat(3, axis=0) >>> offsets = np.array(0, -1, 2) >>> dia_matrix((data, offsets), shape=(4, 4)).toarray() array([1, 0, 3, 0], [1, 2, 0, 4], [0, 2, 3, 0], [0, 0, 3, 4])
>>> from scipy.sparse import dia_matrix >>> n = 10 >>> ex = np.ones(n) >>> data = np.array(ex, 2 * ex, ex) >>> offsets = np.array(-1, 0, 1) >>> dia_matrix((data, offsets), shape=(n, n)).toarray() array([2., 1., 0., ..., 0., 0., 0.], [1., 2., 1., ..., 0., 0., 0.], [0., 1., 2., ..., 0., 0., 0.], ..., [0., 0., 0., ..., 2., 1., 0.], [0., 0., 0., ..., 1., 2., 1.], [0., 0., 0., ..., 0., 1., 2.])