问题
I am looking for something comparable to the "where 'var' in (...)" statement in MySQL.
My code is as follows:
data<-data.frame(id=10001:10030,cc1=rep(c("a","b","c"),10))
attach(data)
data$new<-ifelse(cc1=="a"|cc1=="b",1,0)
What is a better way to include a list of strings in the ifelse instead of using | ?
Something like: ifelse(cc1 in ('a','b'),1,0)
Many Thanks!
回答1:
ifelse(cc1 %in% c("a", "b"), 1, 0)
Or simply:
as.numeric(data$cc1 %in% c("a", "b"))
Avoid using attach though. It makes things messy.
回答2:
I'll just throw this one into the mix
> (!as.numeric(data$cc1) > 2)+0
## [1] 1 1 0 1 1 0 1 1 0 1 1 0 1 1 0 1 1 0 1 1 0 1 1 0 1 1 0 1 1 0
来源：https://stackoverflow.com/questions/23617166/r-string-list-in-ifelse