R/monthly_summary.R

In Tomhigg/TamsatTools: Download and process TAMSAT rainfall estimates

#' Monthy; Summary Statistics
#'
#' Calculates monthly statistical summaries of rainfall for each month for a defined period
#'
#'  Note: There seems to be some problem with some 1983 layers, for ease stick to 1984+
#'
#' @param download_folder Folder containing the downloaded monthly estimates from tamsat_all_download
#' @param stat statistic to calculate, must be compatible with raster::calc()
#' @param period Years as interger(s) for which statistics will be calculated
#' @param months months to calculate eg c(1:12), c(1,4,6,10:12)
#' @param ex any object for which extent can be calculated


monthly_summary <- function(download_folder, months, period, stat, ex) {

    dir_list <- list.dirs(path = download_folder, full.names = T, recursive = F)

    dirs_to_use <- dir_list[grep(pattern = paste(period, collapse = "|"), x = dir_list)]

    all_files <- vector()

    for (i in dirs_to_use) {
        files_to_join <- list.files(path = i, pattern = ".nc", full.names = T, recursive = T)
        all_files <- c(all_files, files_to_join)
    }


    ### change this for an if orig statement
    all_files_test <- all_files[-grep(pattern = "orig.nc", x = all_files)]


    monthy_stats <- stack(sapply(X = months, FUN = function(i) {

        if (i < 10) {
            i <- paste0(0, i)
        }

        monthCode <- paste0("/", i, "/")


        year_paths <- all_files[grep(pattern = monthCode, x = all_files)]

        rasStack <- stack(sapply(year_paths, raster))
        if (is.null(ex) == FALSE) {
            rasStack <- crop(x = rasStack, y = ex)
        }
        summary_statistics <- calc(x = rasStack, fun = stat)
    }))

    months_names <- c("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November",
        "December")

    months_labels <- months_names[c(months)]
    names(monthy_stats) <- months_labels



    return(monthy_stats)
}