R/e.r

In mapsRinteractive: Local Adaptation and Evaluation of Raster Maps

#' @title e
#'
#' @description Calculates the Nash-Sutcliffe modelling efficiency (E)
#' from observed and predicted values.
#'
#' @param observed Numeric vector of observed values
#'
#' @param predicted Numeric vector of predicted values. The length shall be
#' the same as for observed.
#'
#' @return The Nash-Sutcliffe modelling efficiency (E) calculated from observed and
#' predicted values.
#'
#' @details E = 1 - sum(observed - predicted)/sum(observed - mean (observed))
#'
#' @references Nash, J. E., & Sutcliffe, J. V. (1970). River flow forecasting
#' through conceptual models part I—A discussion of principles. Journal of
#' hydrology, 10(3), 282-290.
#'
#' @examples
#' o<-1:5
#' p<-c(2,2,4,3,5)
#' e(observed=o, predicted=p)
#'
#' @export
e<-function(observed, predicted){
  return(1-(sum((observed-predicted)^2)/sum((observed-mean(observed))^2)))
}