R/tempe.R

In araiho/linkages_package: A Linked Forest Productivity - Soil Process Model

##' @title LINKAGES tempe function
##' @author Ann Raiho
##'
##' @param temp.vec  mean temperature for each month
##'
##' @description Calculates total growing degree days for each year, i
##'
##' @return degd total growing degree days for each year
##' @export
##'

tempe <- function(temp.vec){
  ddbase <- 5.56
  days = c(31.,28.,31.,30.,31.,30.,31.,31.,30.,31.,30.,31.)
  temp.vec[temp.vec < ddbase] <- ddbase

  degd <- sum ( (temp.vec-ddbase) * days )

  return(degd)
}

tempe.old <- function(temp.vec){

  ddbase = 5.56 #temp above which degree days are counted
  degd = 0
  days = c(31.,28.,31.,30.,31.,30.,31.,31.,30.,31.,30.,31.)

  #sum degree days for consecutive months
  for(i in 1:12){

    if(temp.vec[i] < ddbase) next
    degd <- degd + (temp.vec[i] - ddbase) * days[i]

  }
  return(degd)
}

#profile
library(microbenchmark)

#test
temp.vec <- c(1,2,3,4,5,6,7,8,9,10,11,12)
microbenchmark( tempe(temp.vec), tempe.old(temp.vec) )