ifelse停止條件-有解無憂

我有一個關于 Rock, Paper, Scissors, Lizard, Spock 游戲的問題。我有以下代碼

    dataTable <- matrix(data = NA, nrow = 25, ncol = 3, byrow = TRUE)

dataTable <- as.data.frame(dataTable)
colnames(dataTable) <- c("Player-1", "Player-2", "Outcome")

## Fill in columns

dataTable[, 1] <- c(rep("Rock", 5), rep("Paper", 5), rep("Scissors", 5), 
                    rep("Lizard", 5), rep("Spock", 5))

dataTable[, 2] <- c(rep(c("Rock", "Paper", "Scissors", "Lizard", "Spock"), 5))
# Filling In The Outcome Column:

outcome_col <- c("Draw!", "Player 2 Wins!", "Player 1 Wins!", "Player 1 Wins!", "Player 2 Wins!",
                 "Player 1 Wins!", "Draw!", "Player 2 Wins!", "Player 2 Wins!", "Player 1 Wins!",
                 "Player 2 Wins!", "Player 1 Wins!", "Draw!", "Player 1 Wins!", "Player 2 Wins!",
                 "Player 2 Wins!", "Player 1 Wins!", "Player 2 Wins!", "Draw!", "Player 1 Wins!",
                 "Player 1 Wins!", "Player 2 Wins!", "Player 1 Wins!", "Player 2 Wins!", "Draw!")


# Place outcome_col as third column and convert as factors:


dataTable[, 3] <- as.factor(outcome_col)



sheldon_game<-function(A,B){
  for (i in 1:nrow(dataTable)){
    if (A!=dataTable[i,1] & B!=dataTable[i,2]){
      stop("Parameters out of bound")
    } else 
      if (A==dataTable[i,1] & B==dataTable[i,2]){
      res<-dataTable[i,3]
    }
  }
  return(res)
  }

sheldon_game("Scissors","Paper")

在最后一個函式 sheldon_game 中，如果插入的不是（巖石、紙、剪刀、蜥蜴、史波克），我想列印錯誤訊息。但是即使引數在串列中，它也會不斷地將結果顯示為錯誤訊息。

uj5u.com熱心網友回復：

問題是您正在測驗以查看每一行是否匹配，并且由于輸入資料將僅匹配一行，因此您總是會收到錯誤訊息。您的代碼可以修改如下：

sheldon_game<-function(A,B){
  for (i in 1:nrow(dataTable)){
    if (! A %in% unique(dataTable[ ,1]) | ! B %in% unique(dataTable[ ,2])){
      stop("Parameters out of bound")
    } else 
      if (A==dataTable[i,1] & B==dataTable[i,2]){
      res<-dataTable[i,3]
    }
  }
  return(as.character(res))
  }

這將檢查以確保包含這些值，但會有更簡單的方法來做到這一點。對該return行的修改使 R 無法列出因子水平。

作為參考，這將利用 R 中的矢量化：

sheldon_game<-function(A, B) {
    Avals <- unique(dataTable[, 1])
    Bvals <- unique(dataTable[, 2])
    if(A %in% Avals & B %in% Bvals) {
        idx <- which(A==dataTable[, 1] & B==dataTable[, 2])
        return(as.character(dataTable[idx, 3]))
    } else return("Parameters out of bound!")
}

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標籤：r for循环 if 语句

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