`scipy.ndimage._measurements:mean`

source: /scipy/ndimage/_measurements.py :760

Signature

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

Summary

Calculate the mean of the values of an array at labels.

Parameters

input : array_like: Array on which to compute the mean of elements over distinct regions.
labels : array_like, optional: Array of labels of same shape, or broadcastable to the same shape as input. All elements sharing the same label form one region over which the mean of the elements is computed.
index : int or sequence of ints, optional: Labels of the objects over which the mean is to be computed. Default is None, in which case the mean for all values where label is greater than 0 is calculated.

Returns

out : list: Sequence of same length as index, with the mean of the different regions labeled by the labels in index.

Notes

Array API Standard Support

mean has experimental support for Python Array API Standard compatible backends in addition to NumPy. Please consider testing these features by setting an environment variable SCIPY_ARRAY_API=1 and providing CuPy, PyTorch, JAX, or Dask arrays as array arguments. The following combinations of backend and device (or other capability) are supported.

====================  ====================  ====================
Library               CPU                   GPU
====================  ====================  ====================
NumPy                 ✅                     n/a                 
CuPy                  n/a                   ✅                   
PyTorch               ✅                     ⛔                   
JAX                   ⚠️ no JIT             ⛔                   
Dask                  ⚠️ computes graph     n/a                 
====================  ====================  ====================

See dev-arrayapi for more information.

Examples

from scipy import ndimage
import numpy as np
a = np.arange(25).reshape((5,5))
labels = np.zeros_like(a)
labels[3:5,3:5] = 1
index = np.unique(labels)
labels
index

✓

ndimage.mean(a, labels=labels, index=index)

✗

Aliases

scipy.ndimage.mean