R/set.R

In krzjoa/matricks: Useful Tricks for Matrix Manipulation

#' @name set_values
#' @title Set multiple values useing one function call
#' @param mat a matrix object
#' @param ... formulae; left hand values should be two-element interger vectors and right-hand: a single-value numeric
#' @return matrix
#' @description
#' This functions allows to set multiple elements of a matrix
#' instead of using annoying step-by-step assignment by
#' mat[1,2] <- 2
#' mat[2,3] <- 0.5
#' etc.
#' @examples
#' mat <- matrix(0, 4, 5)
#' set_values(mat, c(1,1) ~ 5, c(3, 4) ~ 0.3)
#' @export
set_values<- function(mat, ...){

  exprs <- list(...)

  is.formula <- sapply(exprs, function(x) inherits(x, 'formula'))

  if(!all(is.formula))
    stop(paste0("Following arguments are not formulae: ", exprs[!is.formula]))

  for(expr in exprs){
    args <- strsplit(as.character(expr), "~", fixed = TRUE)
    args <- args[args != ""]
    lh <- eval(parse(text = args[[1]]))
    rh <- as.numeric(args[[2]])
    mat[lh[1], lh[2]] <- rh
  }
  mat
}

#' @rdname set_values
#' @export
sv <- set_values