findpeaks

findpeaks(y, x=1:length(y); min_height=minimum(y), min_prom=minimum(y), min_dist=0, threshold=0; xsorted::Bool=false)
or
    
findpeaks(D::GMTdataset; min_height=D.bbox[1], min_prom=zero(D[1]), min_dist=0, threshold=0; xsorted::Bool=false)

Returns indices of local maxima (sorted from highest peaks to lowest) in 1D array of real numbers. Similar to MATLAB's findpeaks().

A local peak is a data sample that is either larger than its two neighboring samples or is equal to Inf. The peaks are output in order of occurrence. This function is from the Findpeaks.jl package.

Args

• y: Input data, specified as a vector. y must be real and must have at least three elements.

• x: Locations, specified as a vector or a datetime array. x must increase monotonically and have the same length as y. If x is omitted, then the indices of y are used as locations.

• D: Alternatively to y and x you can provide a GMTdataset with two, x,y (or more), columns.

Kwargs

• min_height: Minimum peak height, specified as a real scalar. Use this argument to have findpeaks return only those peaks higher than min_height.

• min_prom: Minimum peak prominence, specified as a nonnegative real scalar. Use this argument to have findpeaks return only those peaks that have a relative importance of at least min_prom (see Prominence).

• min_dist: Minimum peak separation (keeping highest peaks). When you specify a value for this option, the algorithm chooses the tallest peak and ignores all peaks within min_dist of it.

• threshold: Minimal difference (absolute value) between peak and neighboring points. Use this argument to have findpeaks return only those peaks that exceed their immediate neighboring values by at least the value of threshold.

• xsorted: If true, the indices of local maxima are sorted in ascending order of x. Default is to sort by amplitude.

Returns

• peaks: A vector of indices of local maxima (sorted from highest peaks to lowest when xsorted=false).

Examples

using GMT

D = gmtread(TESTSDIR * "assets/example_spectrum.txt");
peaks = findpeaks(D, min_prom=1000.);

plot(D, title="Prominent peaks")
scatter!(D[peaks,:], mc=:red, show=true)

using GMT

D = gmtread(TESTSDIR * "assets/example_spectrum.txt");
peaks = findpeaks(D, min_dist=0.2)

plot(D, title="Peaks at least 0.2 units apart")
scatter!(D[peaks,:], mc=:red, show=true)