`scipy.io._mmio:mmwrite`

source: /scipy/io/_mmio.py :136

Signature

   def     mmwrite (    target    ,    a    ,    comment    =  ''   ,    field    =  None   ,    precision    =  None   ,    symmetry    =  None     )

Summary

Writes the sparse or dense array a to Matrix Market file-like target.

Parameters

target : str or file-like: Matrix Market filename (extension .mtx) or open file-like object.
a : array like: Sparse or dense 2-D array.
comment : str, optional: Comments to be prepended to the Matrix Market file.
field : None or str, optional: Either 'real', 'complex', 'pattern', or 'integer'.
precision : None or int, optional: Number of digits to display for real or complex values.
symmetry : None or str, optional: Either 'general', 'symmetric', 'skew-symmetric', or 'hermitian'. If symmetry is None the symmetry type of 'a' is determined by its values.

Returns

: None

Examples

from io import BytesIO
import numpy as np
from scipy.sparse import coo_array
from scipy.io import mmwrite

✓

Write a small NumPy array to a matrix market file. The file will be written in the ``'array'`` format.

a = np.array([[1.0, 0, 0, 0], [0, 2.5, 0, 6.25]])
target = BytesIO()
mmwrite(target, a)

✓

print(target.getvalue().decode('latin1'))

✗

Add a comment to the output file, and set the precision to 3.

target = BytesIO()
mmwrite(target, a, comment='\n Some test data.\n', precision=3)

✓

print(target.getvalue().decode('latin1'))

✗

Convert to a sparse matrix before calling ``mmwrite``. This will result in the output format being ``'coordinate'`` rather than ``'array'``.

target = BytesIO()
mmwrite(target, coo_array(a), precision=3)

✓

print(target.getvalue().decode('latin1'))

✗

Write a complex Hermitian array to a matrix market file. Note that only six values are actually written to the file; the other values are implied by the symmetry.

z = np.array([[3, 1+2j, 4-3j], [1-2j, 1, -5j], [4+3j, 5j, 2.5]])
z

✓

target = BytesIO()
mmwrite(target, z, precision=2)

✓

print(target.getvalue().decode('latin1'))

✗

Aliases

scipy.io._mmio.mmwrite