R ifel 语句

Question

我是 R 的新手。我有以下由字符组成的数据集（数据框）：

"Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "N" "N" "Y" "Y" "Y"
"Y" "Y" "Y" "Y" "Y" "N" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "N" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "N" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "Y" "Y" "Y" "Y" "Y" "N" "Y" "Y" "Y" "N" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "Y" "Y" "N" "Y" "Y" "Y" "Y" "N" "Y" "Y" "Y" "Y" "N" "Y" "Y" "Y"
"Y" "Y" "Y" "Y" "Y" "Y" "N" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "Y" "Y" "Y" "Y" "Y" "N" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "Y" "N" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y" "Y"
"Y" "Y" "Y" "Y" "Y" "Y" "N" "Y" "Y" "Y" "Y" "Y" "Y" "N" "Y" "Y"

我想用 1 替换Y ，用 0 替换N因此我使用以下表达式：

ifelse(Dataset$A=="N",Dataset$A<-0,Dataset$A<-1)  

虽然， ifelse函数的结果是正确的，但是在打印变量时我得到了这个：

"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"

你有什么提示吗？

Answer 1

将另一个变量 B 添加到数据集并使用 ifelse 函数，其中“N”值为 0，“Y”值为 1

Dataset$B <- ifelse(Dataset$A=="N",0,1)

或者您可以在相同的变量上使用 ifelse 函数

Dataset$A <- ifelse(Dataset$A=="N",0,1)

Answer 2

你也可以这样做：

Dataset$A <- (Dataset$A=="Y")*1

Answer 3

ifelse 可以工作，但另一种选择是使用 switch() 函数：

vec <- c("Y","Y","Y","N","N","Y")
sapply(vec, switch, "Y"=1,"N"=0)

它可以满足您的需求，但对于大小为 1 的向量。然后您将其应用于所有元素。

switch 函数的好处（ifelse 不这样做）是您可以使用任意数量的替换（“A”=1、“B”=2、“C”=3 等...），