peaks {PROcess} | R Documentation

## Peak Detection

### Description

Finds the local maxima, local noise and its associated standard deviations in a vector.

### Usage

    peaks(x, span = 3)
    noise(x, span = 5)
    sigma(x, span = 5)

### Arguments

`x` | a vector.
`span` | a local miximum is defined as an element in a sequence which is greater than all other elements within a window of width ‘span’ centered at that element. The default value is 3, meaning that a peak is bigger than both of its neighbors. Local noise is definedas an element minus the mean of all elements within a window of width ‘span’ centered at that element. Local standard deviation of an element is defined as the standard deviation of all elements within a window of width ‘span’ centered at that element.

### Value

a logical vector of the same length as ‘series’ indicating where the peaks are.

### Author(s)

Xiaochun Li

### Examples

    x <- seq(0, 10*pi, by=0.1)
    y <- sin(x)*x
    plot(x,y, type="l")
    is.max <- peaks(y)
    points(x[is.max],y[is.max], pch=21, bg="red")
    legend(2, 25, legend = "Peaks",pch = 19, col="red", bty = "n")

    # can be used for local minima too:
    # is.min <- peaks(-y)
    # points(x[is.min],y[is.min], pch=21, bg="blue")

[Package PROcess version 1.70.0 Index]