Instalar y cargar paquetes

packages <- c("ncdf4",
              "raster",
              "rgdal",
              "maps",
              "dplyr",
              "ggplot2",
              "lubridate",
              "xts")
installed_packages <- packages %in% rownames(installed.packages())
if (any(installed_packages == FALSE)) {
  install.packages(packages[!installed_packages])
}
invisible(lapply(packages, library, character.only=TRUE))

Funciones

numberOfDays <- function(date) {
  m <- format(date, format="%m")
  while (format(date, format="%m")==m) {
    date <- date + 1
  }
  return(as.integer(format(date-1,format="%d")))
}