`islocalmax`

Marks the local maxima of a vector.

Category: Data Import and Analysis > Preprocessing Data

Syntax

TF = islocalmax(A)

true where an element is larger than its neighbors.

[TF, P] = islocalmax(A)

Also returns the prominence of each peak.

TF = islocalmax(A, 'MinProminence', m)

Keeps only peaks whose prominence is at least m.

Description

A local maximum is a point strictly greater than the neighbors on both sides. Prominence measures how far a peak rises above the lowest contour that separates it from a higher peak, so it filters out small ripples caused by noise.

Use find(TF) to get the positions of the peaks.

Input arguments

A: Numeric vector or matrix (columns are analyzed).
'MinProminence': Minimum height a peak must stand above its surroundings.

Output arguments

TF: Logical array the size of A.
P: Prominence values, zero at points that are not peaks.

Example

Peaks and prominence

x = [1 3 1 4 1];
[tf, p] = islocalmax(x)
islocalmax(x, 'MinProminence', 3)

Output

tf = 1×5 logical array

   0   1   0   1   0
p = 1×5

     0     2     0     3     0
ans = 1×5 logical array

   0   0   0   1   0

islocalmax