ItemSimulation_v3

library(tidyverse)

## ── Attaching packages ─────────────────────────────────────── tidyverse 1.3.1 ──

## ✔ ggplot2 3.3.6     ✔ purrr   0.3.4
## ✔ tibble  3.1.7     ✔ dplyr   1.0.9
## ✔ tidyr   1.2.0     ✔ stringr 1.4.0
## ✔ readr   2.1.2     ✔ forcats 0.5.1

## ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
## ✖ dplyr::filter() masks stats::filter()
## ✖ dplyr::lag()    masks stats::lag()

itemSim <- setRefClass(
  "itemSim",
  fields = list(
    s1Time = "numeric",
    s2Time = "numeric",
    reTime = "numeric",
    tTime = "numeric"
  ),
  methods = list(
    initialize = function(reproProb){
      stopifnot(is.numeric(reproProb))
      s1Time <<- runif(1, 50, 100)
      s2Time <<- rnorm(1, 50, 5)
      reTime <<- 0
      if(runif(1,0,1)<=reproProb){
        reTime <<- runif(1, 20, 40)
      }
      tTime <<- s1Time+s2Time+reTime
    }
  )
)

setMethod("show",
          "itemSim",
          function(object){
            cat("Total Time to produce this item is",object$tTime, "\n")
})

runSimulation <- function(numTrials, reproProb, timeLimit){
  totalTime = list()
  counter = 0
  
  for(i in 1:numTrials){
    trial = itemSim(reproProb)
    totalTime <- append(totalTime, trial$tTime)
    if(trial$tTime >= timeLimit){
      counter = counter+1
    }
  }
  writeLines(strwrap(paste("Total time Expected Value is", signif(mean(as.numeric(totalTime)),5))))
  writeLines(strwrap(paste("Total Time STD is", signif(sd(as.numeric(totalTime)),4))))
  writeLines(strwrap(paste("Probability that total time is more than", timeLimit, "is", (counter/numTrials), collapse = " ")))
  return(totalTime)
}

results <- as.data.frame(as.numeric(runSimulation(10000, .05, 150))) %>% 
  rename(results = `as.numeric(runSimulation(10000, 0.05, 150))`)

## Total time Expected Value is 126.33
## Total Time STD is 16.46
## Probability that total time is more than 150 is 0.0633

bw <- 2*IQR(results$results)/length(results$results)^(1/3)

ggplot(results,
       aes(x = results))+
  geom_histogram(binwidth = bw,
                 fill = 'green',
                 color = 'black',
                 alpha = .5)+
  labs(title = "Distribution of item Simulation",
       x = "Time (Minutes)",
       y = "Amount of Items")+
  hrbrthemes::theme_ft_rc()