# R/vectorHaromics.R In environmentalinformatics-marburg/Rsenal: Magic R Functions for Things Various

#### Documented in vectorHarmonics

```#' Fit harmonic trend model to time-series values
#'
#' @description This is a wrapper function around \code{\link{harmonic}} from
#' the \code{TSA} package that constructs harmonic functions for fitting a
#' harmonic trend model.
#'
#' @param x Numeric. A vector containing time-series values.
#' @param frq Integer, defaults to 12 (months). The number of observations per
#' unit of time. See \code{\link{ts}}.
#' @param st Numeric. A vector containing start year and month.
#' @param nd Numeric. A vector containing end year and month.
#' @param m Integer, defaults to 2. The number of pairs of harmonic functions to
#' @param fun Aggregating function to be applied to the fitted values.
#'
#' @return
#' A numeric vector.
#'
#' @author
#' Tim Appelhans
#'
#' @seealso
#'
#' @export vectorHarmonics
#' @aliases vectorHarmonics
vectorHarmonics <- function(x,
frq = 12L,
st = c(1982, 1),
nd = c(1986, 12),
m = 2L,
fun = median) {

xts <- ts(x, start = st, end = nd, frequency = frq)
har <- TSA::harmonic(xts, m = m)
mod <- lm(xts ~ har)
fit <- ts(fitted(mod), start = st, end = nd, frequency = frq)
fit.med <- apply(matrix(fit, ncol = frq, byrow = TRUE), 2, FUN = fun)

return(fit.med)

}
```
environmentalinformatics-marburg/Rsenal documentation built on Sept. 23, 2018, 5:17 a.m.