R/lappend.R

In muschellij2/atropos: Core Software Infrastructure for 'ANTsR'

#' Simple list append tool
#'
#' Append an item to a list , creating a new list or combine two lists
#'
#'
#' @param lst list to which you will append the 2nd item
#' @param obj to be added to the list
#' @return outputs the appended list
#' @author Avants BB, the internet
#' @examples
#'
#' mat<-replicate(100, rnorm(20))
#' mat2<-replicate(100, rnorm(20))
#' mylist<-list(mat)
#' mylist<-lappend( mylist, mat2 )
#' mylist<-lappend( mat2, mylist)
#' mylist<-lappend( mylist, mylist)
#' lappend( 1, 1)
#'
#' @export lappend
lappend <- function(lst, obj) {
  if (typeof(obj) != "list") {
    lst[[length(lst) + 1]] <- obj
    return(lst)
  }
  if (typeof(obj) == "list" & typeof(lst) != "list") {
    lstout <- list(lst)
    for (i in 1:length(obj)) {
      lstout[[length(lstout) + 1]] <- obj[[i]]
    }
    return(lstout)
  }
  if (typeof(obj) == "list" & typeof(lst) == "list") {
    for (i in 1:length(obj)) {
      lst[[length(lst) + 1]] <- obj[[i]]
    }
    return(lst)
  } else return(NA)
}