MALDIquant (version 1.0)

findLocalMaxima-methods: Find local maxima in a MassSpectrum object.

Description

This methods looks for local maxima in mass spectrometry data (represented by a MassSpectrum object).

Usage

## S3 method for class 'MassSpectrum':
findLocalMaxima(object, 
    halfWindowSize=20);

Arguments

object

MassSpectrum object

halfWindowSize

half window size The resulting window reaches from mass[currentIndex-halfWindowSize] to mass[currentIndex+halfWindowSize].

Value

• Returns a two column matrix (first column: mass, second column: intensity) of the founded maxima.

See Also

MassSpectrum, detectPeaks,MassSpectrum-method

Examples

## load library
library("MALDIquant");

## load example data
data("spectra", package="MALDIquant");

## choose only the first mass spectrum
s <- spectra[[1]];

## transform intensities
s <- transformIntensity(s, sqrt);

## remove baseline
s <- removeBaseline(s);

## plot spectrum
plot(s);

## find local maxima
m <- findLocalMaxima(s);

## draw maxima on the plot
points(m, col="red");