[R] Filter out some levels?

[Douglas Bates]

Christian Schulz <ozric at web.de> writes:

> how is it possible to cut some levels from one factor to  subsetting  a 
> data.frame on?
> 
> subdata <- subset(data, data$FACTOR="1" | 
> data$FACTOR="BETA" | data$FACTOR="XY")
> ???
> 
> Maybe a modifcation here is better, but how?
> mergex[mergex$PLZX %in% levels(mergex$PLZX) ,]

Use %in%

subdata <- subset(data, FACTOR %in% c("1", "BETA", "XY"))