getRhoFirstOrderFun: Produces a function that uses a first-order autocorrelation...

In USGS-R/loadflex: Models and Tools for Watershed Flux Estimates

Produces a function that uses a first-order autocorrelation model to estimate the correlation between two dates.

Description

Produces a function of the form described in correlations-1D.

getRhoFirstOrderFun accepts an assumed or empirically estimated value of \rho (rho), the correlation coefficient in the first-order autocorrelation model:

cor(y(t1), y(t2)) = \rho^\tau

where

\tau = y(t2) - y(t1)

and \tau is in the same units as those used to estimate \rho (rho). To ensure that the units are the same, this function also accepts a time.step argument indicating the interval between two successive values in the time series used to estimate \rho (rho). The function returned by getRhoFirstOrderFun takes responsibility for matching the units of date1 and date2 to those of rho.

Usage

getRhoFirstOrderFun(rho, time.step = as.difftime(1, units = "hours"))

Arguments

rho	The coefficient of the first-order autocorrelation model, either asserted by the user or estimated by estimateRho.
time.step	difftime. The time.step of the time series used to estimate rho. It is essential to use the right units; as.difftime(1, units="hours") is quite different from as.difftime(1, units="days").

Value

A function that accepts two date arguments and returns the predicted correlation between those two dates. One of the date arguments may be a vector as long as the other is scalar. This function takes the form, function(date1, date2) with arguments as defined for rhoEqualDates and rho1DayBand.

USGS-R/loadflex documentation built on July 26, 2023, 9:54 p.m.