R ifel 语句
[英]R ifelse statement
问题描述
I'm pretty new at R. I have the following data set (data frame) composed by characters:
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"
and I want to replace Y with 1 and N with 0. Thus I'm using the following expression: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$A<-1)
Although, the result from the ifelse function is correct but when printing the variable I m getting this:虽然， ifelse函数的结果是正确的，但是在打印变量时我得到了这个：
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
"1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1" "1"
Do you have any hint why?你有什么提示吗？
3 个解决方案
解决方案1
2 已采纳 2016-09-22 09:12:22
Add another variable B to dataset and use ifelse function where you get 0 for "N"and 1 for "Y" values将另一个变量 B 添加到数据集并使用 ifelse 函数，其中“N”值为 0，“Y”值为 1
Dataset$B <- ifelse(Dataset$A=="N",0,1)
or you can use ifelse function on same variable as或者您可以在相同的变量上使用 ifelse 函数
Dataset$A <- ifelse(Dataset$A=="N",0,1)
解决方案2
1 2016-09-22 09:25:00
你也可以这样做：
Dataset$A <- (Dataset$A=="Y")*1
解决方案3
1 2016-09-22 14:01:24
ifelse can work, but an other option is to use the switch() function: 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)
it does what you want, but for vectors of size 1. You then sapply it through all of your elements.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。
The good thing about switch function (that ifelse doesn't do) is that you can use as many substitution as you want ("A"=1, "B"=2, "C"=3, etc...), 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...），
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