R/sens_slo.R

In ERottler/meltimr: Shiny App to investigate GRDC runoff data with regard to changes in runoff timing

#' Sen´s slope
#'
#' Calculation of linear trend using Sen´s slope using package 'zyp'.
#'
#' @param data_in  Numeric vector.
#' @param cover_thresh Trend only calculated when percentage of NAs in data_in does not exceed cover threshold (0-1)
#' @export
sens_slo <- function(data_in, cover_thresh = 0.9){

  if(length(which(is.na(data_in))) / length(data_in) > (1-cover_thresh)){
    sens_slo <-  NA
  }else{
    time_step <- 1:length(data_in)
    sens_slo <- as.numeric(zyp::zyp.sen(data_in~time_step)$coefficients[2])
    #sens_slo <- as.numeric(zyp.trend.vector(data_in, method = "zhang", conf.intervals = F)[2])
  }
  return(sens_slo)
}