R/flowtabmat.R

In cartograflow: Filtering Matrix for Flow Mapping

#' @title Changing the format of a flow dataset
#' @description Transform a flow dataset from long to matrice format, and vice versa. 
#' Square matrice.
#' @param tab flow dasaset, in matrice or long format
#' @param matlist choose "matrice" or "long" for the resulting format. See Details.
#' @return a flow dataset in matrice or in long format
#' @export
#' @details
#' - matlist="M" from long (3 columns : origin, destination, flow) to matrice format [n*n];\cr
#' - matlist="L" from matrice to long format.
#' @examples
#' library(cartograflow)
#' data(flowdata)
#' # 1: From long to matrix format (n*m)
#' matFlow <- flowtabmat(flows, matlist = "M")
#' # 2: From matrix to long format [i,j,Fij]
#' listflow <- flowtabmat(matFlow, matlist = "L")
#' @importFrom reshape2 melt
#' @importFrom reshape2 acast

flowtabmat <- function(tab, matlist) {
                      if (matlist == "L") {
                        if (nrow(tab) != ncol(tab)) {
                          message("your matrix is not usable, please use the function cartograflow::flowstructmat()")
                          l.liste <- melt(tab)
                        }
                        if (nrow(tab) == ncol(tab)) {
                          l.liste <- melt(tab, na.rm = TRUE)
                        }
                        names(l.liste) <- c("i", "j", "ydata")
                        return(l.liste)
  }
  if (matlist == "M") {
                      m.mat <- acast(tab, i ~ j)
                      for (i in 1:nrow(m.mat)) {
                        for (j in 1:ncol(m.mat))
                        {
                          if (is.na.data.frame(m.mat[i, j]) == TRUE) {
                            m.mat[i, j] <- 0
                          }
                        }
                      }
                      if (nrow(m.mat) != ncol(m.mat)) {
                        message("warning:your matrix is not square!")
                      }
                      if (nrow(m.mat) == ncol(m.mat)) {
                        message("great:your matrix is square!")
                      }
                      return(m.mat)
                    }
}