`scipy.ndimage._measurements:variance`

source: build-install/usr/lib/python3.14/site-packages/scipy/ndimage/_measurements.py:813

Signature

def variance(input, labels = None, index = None)

Summary

Calculate the variance of the values of an N-D image array, optionally at specified sub-regions.

Parameters

input : array_like: Nd-image data to process.
labels : array_like, optional: Labels defining sub-regions in input. If not None, must be same shape as input.
index : int or sequence of ints, optional: labels to include in output. If None (default), all values where labels is non-zero are used.

Returns

variance : float or ndarray: Values of variance, for each sub-region if labels and index are specified.

Examples

import numpy as np
a = np.array([[1, 2, 0, 0],
              [5, 3, 0, 4],
              [0, 0, 0, 7],
              [9, 3, 0, 0]])
from scipy import ndimage

✓

ndimage.variance(a)

✗

np.float64(7.609375)

Features to process can be specified using `labels` and `index`:

lbl, nlbl = ndimage.label(a)

✓

ndimage.variance(a, lbl, index=np.arange(1, nlbl+1))

✗

array([2.188, 2.25 , 9.   ])

If no index is given, all non-zero `labels` are processed:

ndimage.variance(a, lbl)

✗

np.float64(6.1875)

Aliases

scipy.ndimage.variance