Finding local maxima and minima in R

peaks.R

#' Find local maxima and minima in R
#' @param x numeric vector to search for peaks
#' @param partial whether or not to include partial peaks
#'        at the beginning or end of the vector
#' @param decreasing whether to find peaks (the default)
#'        or valleys
which.peaks <- function(x,partial=TRUE,decreasing=FALSE){
  if (decreasing){
    if (partial){
      which(diff(c(TRUE,diff(x)<=0,FALSE))>0)
    }else {
      which(diff(diff(x)<=0)>0)
    }    
  }else {
    if (partial){
      which(diff(c(TRUE,diff(x)>=0,FALSE))<0)
    }else {
      which(diff(diff(x)>=0)<0)
    }
    
  }
}