peaks_fwhm {alkahest} R Documentation

## Half-Width at Half-Maximum

### Description

Estimates the Half-Width at Half-Maximum (FWHM) for a given peak.

### Usage

peaks_fwhm(x, y, ...)

## S4 method for signature 'numeric,numeric'
peaks_fwhm(x, y, center)

## S4 method for signature 'ANY,missing'
peaks_fwhm(x, center)


### Arguments

 x, y A numeric vector. If y is missing, an attempt is made to interpret x in a suitable way (see grDevices::xy.coords()). ... Currently not used. center A numeric value giving the peak position in x units.

### Details

It tries to get the smallest possible estimate.

### Value

A numeric value.

### Author(s)

N. Frerebeau

Other peaks detection methods: peaks_find()

### Examples

## X-ray diffraction
data("XRD")

## 4S Peak Filling baseline
baseline <- baseline_peakfilling(XRD, n = 10, m = 5, by = 10, sparse = TRUE)

plot(XRD, type = "l", xlab = expression(2*theta), ylab = "Count")
lines(baseline, type = "l", col = "red")

## Correct baseline
XRD <- signal_drift(XRD, lag = baseline, subtract = TRUE)

## Find peaks
peaks <- peaks_find(XRD, SNR = 3, m = 11)

plot(XRD, type = "l", xlab = expression(2*theta), ylab = "Count")
lines(peaks, type = "p", pch = 16, col = "red")
abline(h = attr(peaks, "noise"), lty = 2) # noise threshold

## Half-Width at Half-Maximum
x <- seq(-4, 4, length = 1000)
y <- dnorm(x)

peaks_fwhm(x, y, center = 0) # Expected: 2 * sqrt(2 * log(2))


[Package alkahest version 1.1.1 Index]