older/class_specific_material/SDS100/R/do_it.R

In emeyers/ClassTools: Code useful for classes

# A function do_it() that runs code many times.
# It is a simplified version of the mosiac do() that returns a vector only.
# The idea and code are based on the mosaic do() function, which can be found on
# github page at: https://github.com/ProjectMOSAIC/mosaic/blob/master/R/do.R
# The code uses S4 objects.



# the constructor
#' @export

do_it <- function(n=1L) {
  new('doer', n=n)
}





# S4 class definition for runner so that * is appropriately dispatched
#' @export

setClass('doer',
         representation = representation(n='numeric'),
         prototype = prototype(n=1))





# create the * method
# first argument is a runner, the second is any expression
#' @export

setMethod(
  "*",
  signature(e1 = "doer", e2="ANY"),
  function (e1, e2) {

    # create a formula for the second argument in the multiplication
    e2_lazy <- lazyeval::f_capture(e2)

    # get n from the n argument in the run constructor
    n = e1@n

   # evaluate the formula n times
   sapply(integer(n), function(...) { lazyeval::f_eval(e2_lazy) } )

})