R/forfor.R

In rcorty/CortyKit: Robert Corty's Utility Functions

#' #' @title forfor
#' #'
#' #' @param l named list of variables to loop over and their values to loop over
#' #' @param e expression to evaluate for every combination of values in l
#' #'
#' #' @details so  forfor(l = list(a = c(1,2), b = c(10, 20)), e = a + b)
#' #           evaluates to c(11, 21, 21, 22)
#' #           as if we had typed for(a in c(1,2)) { for(b in c(10,20)) { a + b }}
#' #' @return
#' #' @export
#' #'
#'
#' forfor <- function(l, e) {
#'
#'   g <- expand.grid(l)
#'
#'   r <- list()
#'   for (i in 1:nrow(g)) {
#'
#'     n <- paste0(colnames(g), '=', unlist(g[i,]), collapse = '_')
#'     r[[n]] <- eval(substitute(e), g[i,])
#'   }
#'
#'   return(r)
#' }