R/Queue.R

In jakeyeung/TissueCiradianAnalysis: Analysis of oscillatory RNASeq data

# Queue data structure in R 
# https://www.researchgate.net/post/What_is_the_queue_data_structure_in_R
new.queue <- function() {
  ret <- new.env()
  ret$front <- new.env()
  ret$front$q <- NULL
  ret$front$prev <- NULL
  ret$last <- ret$front
  return(ret)
}

## add to end of queue
enqueue <- function(queue, add){
  queue$last$q <- new.env()
  queue$last$q$prev <- queue$last
  queue$last <- queue$last$q
  queue$last$val <- add
  queue$last$q <- NULL
}

## return front of queue and remove it
dequeue <- function(queue){
  if (is.empty(queue)) {
    stop("Attempting to take element from empty queue")
  }
  value <- queue$front$q$val
  queue$front <- queue$front$q
  queue$front$q$prev <- NULL
  return(value)
}

is.empty <- function(queue){
  return(is.null(queue$front$q))
}

# TEST
# N = 10
# qq <- new.queue()
# for(i in 1:N){
#   enqueue(qq,i)
# }
# 
# while (! is.empty(qq)) {
#   print(dequeue(qq))
# }