extrema {Tides} | R Documentation |
Calculate maxima and minima of quasi periodic time series. The function works good when the time series is 'smooth enough'. The function will fail when multiple local extrema exist, with a magnitude similar to the extremum extremorum and in an interval larger than [t-T2, t+T2] around the extremum extremorum at time t. When this is the case, this might be solved by adding extra wrappers around the function.
extrema(h, h0, T2 = 5*60*60, hoffset = 3, filtconst = 1)
h |
Water level time series. data frame with time and h column |
h0 |
Reference level, either single valued vector with dimension corresponding to h |
T2 |
'Lower' bound on half the quasi period, but higher than expected stagnant phase; default = 5h |
hoffset |
Offset level, to prevent spurious maxima generation due to small fluctuations |
filtconst |
Filtering constant for smoothing the time series |
a list containing:
HL |
Data frame with extrema |
h |
original water level data frame with additional attributes |
Tom Cox <tom.cox@ua.ac.be>