`scipy.ndimage._measurements:maximum_position`

source: /scipy/ndimage/_measurements.py :1321

Signature

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

Summary

Find the positions of the maximums of the values of an array at labels.

Extended Summary

For each region specified by labels, the position of the maximum value of input within the region is returned.

Parameters

input : array_like

Array_like of values.

labels : array_like, optional

An array of integers marking different regions over which the position of the maximum value of input is to be computed. labels must have the same shape as input. If labels is not specified, the location of the first maximum over the whole array is returned.

The labels argument only works when index is specified.

index : array_like, optional

A list of region labels that are taken into account for finding the location of the maxima. If index is None, the first maximum over all elements where labels is non-zero is returned.

The index argument only works when labels is specified.

Returns

output : list of tuples of ints

List of tuples of ints that specify the location of maxima of input over the regions determined by labels and whose index is in index.

If index or labels are not specified, a tuple of ints is returned specifying the location of the first maximal value of input.

Notes

Array API Standard Support

maximum_position 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.array([[1, 2, 0, 0],
              [5, 3, 0, 4],
              [0, 0, 0, 7],
              [9, 3, 0, 0]])

✓

ndimage.maximum_position(a)

✗

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

lbl = np.array([[0, 1, 2, 3],
                [0, 1, 2, 3],
                [0, 1, 2, 3],
                [0, 1, 2, 3]])

✓

ndimage.maximum_position(a, lbl, 1)

✗

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

ndimage.maximum_position(a, lbl)

✗

If there are no maxima, the position of the first element is returned:

ndimage.maximum_position(a, lbl, 2)

✗

Aliases

scipy.ndimage.maximum_position