Ridge of a wavelet power or coherence spectrum
It finds the ridge of a (cross-)wavelet power or coherence spectrum, subject to criteria concerning: the band of neighboring values to be included in the search area for local maximization, and a scale factor applied to the global maximum defining a minimum level constraint.
The basic concept of ridge determination builds on ideas developed by Huidong Tian and Bernard Cazelles (archived R package WaveletCo). This code is an efficient implementation of this concept, building heavily on the use of matrices in order to minimize computation time in R.
ridge(wavelet.spectrum, band = 5, scale.factor = 0.1)
wavelet.spectrum: (cross-)wavelet power or coherence spectrum in the time/frequency domain
band: lower/upper band of neighboring values in the frequency domain used in the search for local maxima.
Default: 5.
scale.factor: a scale factor applied to the global maximum defining a minimum level constraint.
Default: 0.1.
A matrix of 0s and 1s is returned which determines the course of (cross-)wavelet power or coherence ridge in the time/frequency domain.
Tian, H., and Cazelles, B., 2012. WaveletCo. Available at https://cran.r-project.org/src/contrib/Archive/WaveletCo/, archived April 2013; accessed July 26, 2013.
Angi Roesch and Harald Schmidbauer
Credits are also due to Huidong Tian and Bernard Cazelles whose basic concept of ridge determination has been adopted.