如何获取用户从样本中选择的值？

如何解决如何获取用户从样本中选择的值？

我有一个由“Rolls

我想要做的是让用户从样本中选择两个值，然后我希望将这两个值添加并存储在样本中。 （我不需要对加法中使用的值发生任何事情）

我的主要问题是我一直在使用：

"first_number

这并不能确保他们选择的值在我拥有的样本内。

例如，假设我的样本是 4 5 6 6 2，使用我当前使用的代码，用户可以选择任何值，例如 1、0 甚至 200，即使这些都不是在给定的样本集中。如果我能解决这个问题，那么我接下来要做的事情就会很简单。

非常感谢任何支持

解决方法

可能是这样的：

#Rolls <- c( 4,5,6,2 )

set.seed(100)
Rolls<-sample(1:6,replace=TRUE)
chosen <- c()
ordinals <- c("first","second")

while( length(chosen) < 2 ) {

    cat( "Dice = ",Rolls,"\n" )

    pick <- readline(
        prompt=paste("Please enter the",ordinals[length(chosen)+1],"value you'd like to add: ")
    )

    if( pick %in% Rolls ) {
        chosen <- append( chosen,as.numeric(pick) )
        Rolls <- Rolls[ -match( pick,Rolls ) ]
    } else {
        cat("Whoops,that's not a valid choice!\n")
    }

}

在我的会话中看起来像这样：

Dice =  2 6 3 1 2 
Please enter the first value you'd like to add: 4
Whoops,that's not a valid choice!
Dice =  2 6 3 1 2 
Please enter the first value you'd like to add: 2
Dice =  6 3 1 2 
Please enter the second value you'd like to add: 5
Whoops,that's not a valid choice!
Dice =  6 3 1 2 
Please enter the second value you'd like to add: 3

,

您需要自己控制该逻辑。试试这个功能：

readline_int <- function(...,lo = -Inf,hi = Inf,maxtries = 10) {
  ans <- as.numeric(readline(...))
  while (maxtries > 0 && (anyNA(ans) || ans < lo || ans > hi)) {
    warning("value not within expected bounds: [",lo,",hi,"]")
    maxtries <- maxtries - 1
    ans <- as.numeric(readline(...))
  }
  ans
}

readline_int(prompt="Please enter the first value you'd like to add: ",lo=1,hi=6)
# Please enter the first value you'd like to add: 9
# Warning in readline_int(prompt = "Please enter the first value you'd like to add: ",:
#   value not within expected bounds: [1,6]
# Please enter the first value you'd like to add: 5
# [1] 5