尝试使用replicate调用函数1000次

Question

simulate <- function(bankroll, bet, max_iterations) { #gambler's ruin function 
  iteration = 1 
  while (bankroll > 0 & iteration < max_iterations) {
    win <- sample(0:1, size = 1) #either loos or win 
    if (win) {
      bankroll <- (bankroll + bet)
    } else {
      bankroll <- (bankroll - bet)
    }
    iteration <- iteration + 1 
  } 
  return(list(c(iteration, bankroll))) 
} 

simulate(1000, 100, 100) 

我尝试调用上面的函数1000次来获得向量。然后我需要计算有多少次迭代小于100次。有什么建议吗？谢谢

Answer 1

这是一个使用base的简单版本

simulate <- function(bankroll, bet, max_iterations) { #gambler's ruin function 
  iteration = 1 
  while (bankroll > 0 & iteration < max_iterations) {
    win <- sample(0:1, size = 1) #either loos or win 
    if (win) {
      bankroll <- (bankroll + bet)
    } else {
      bankroll <- (bankroll - bet)
    }
    iteration <- iteration + 1 
  } 
  return(bankroll)
} 

calls <- replicate(n = 1000,expr = simulate(1000, 100, 100))

calls_less_100 <- calls < 100

result <- length(calls[calls_less_100])

result    

probability <- result/length(calls)

probability

Answer 2

这可以简单地简化为：

simulate <- function(bankroll, bet, max_iterations){
         bankroll + bet * sum(sample(c(-1, 1), max_iterations, TRUE))
}

然后你可以这样做：

sum(replicate(1000, simulate(1000, 100, 100))<100)