Selecting cases by ordinal variables in a dataframe in R

Question

I've got many dataframes I have to filter by ordinal likert-scaled variables. Instead of selecting them by x == "Strongly disagree" | x == "Disagree" and so on, I would like to select them by x < 3. How can I do that?

xl <- sample(1:5, 20, replace = T)
x <- factor(xl,labels=c("Strongly disagree","Disagree","Neither agree nor disagree","Agree", "Strongly agree"),ordered=TRUE)
y<-sample(2:40,20)
z<-data.frame(x,y)
a<-subset(z,x == "Strongly disagree" | x == "Disagree")
a

thanks

Answer 1

Ordered factors know that they're orderd, so all you need is:

x < "Agree"
x >= "Disagree"

etc

Answer 2

levels(x)<-seq(1,length(levels(x)),1) #and then do subsetting
z<-data.frame(x,y)
> a<-subset(z,x<3)
> a
   x  y
1  1 12
2  2  5
3  1  8
4  2  9
5  2 15
9  1 33
10 2 27
11 2 13
18 1 11

Note: 1 is strongly disagree, 2 is disagree and so on

Answer 3

Something like this?

z[as.numeric(z$x) < 3, ]