find_peaks {photobiology}

Find peaks in a spectrum

Description

This function finds all peaks (local maxima) in a spectrum, using a user provided size threshold relative to the tallest peak (global maximum) bellow which found peaks are ignored—i.e., not included in the returned value. This is a wrapper built on top of function peaks() from package 'splus2R'.

Usage

find_peaks(x, ignore_threshold = 0, span = 3, strict = TRUE, na.rm = FALSE)

Arguments

x

numeric vector

ignore_threshold

numeric Value between 0.0 and 1.0 indicating the relative size compared to tallest peak threshold below which peaks will be ignored. Negative values set a threshold so that the tallest peaks are ignored, instead of the shortest.

span

integer A peak 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. Use NULL for the global peak.

strict

logical If TRUE, an element must be strictly greater than all other values in its window to be considered a peak.

na.rm

logical indicating whether NA values should be stripped before searching for peaks.

Value

A logical vector of the same length as x. Values that are TRUE correspond to local peaks in the data.

Note

This function is a wrapper built on function peaks from splus2R and handles non-finite (including NA) values differently than splus2R::peaks, instead of giving an error they are replaced with the smallest finite value in x.

See Also

peaks

Other peaks and valleys functions: find_spikes(), get_peaks(), peaks(), replace_bad_pixs(), spikes(), valleys(), wls_at_target()

Examples

with(sun.data, w.length[find_peaks(s.e.irrad)])