R matching more than 2 conditions and return the response value

Question

Hi I have two data set where the first one is a set of index:

ind1<-rep(c(\"E\",\"W\"), times=20)
ind2<-sample(100:150, 40)
y<-c(1:40)
index<-dat         


        

Answer 1

This question is related to match two data.frames based on multiple columns.

You can use interaction or paste as already suggested by Dinre, to match on multiple columns.

#Write the row number of index in x3 which matches
data$x3 <- match(interaction(data[c("x1", "x2")]), interaction(index[c("ind1","ind2")]))

#In case you want to return 0 instead of NA for nomatch
data$x3 <- match(interaction(data[c("x1", "x2")]), interaction(index[c("ind1","ind2")]), nomatch=0)

#Instead of >interaction< you could also use paste as already suggested by Dinre
data$x3 <- match(paste(data$x1, data$x2), paste(index$ind1, index$ind2))