firstlastobs {doBy} | R Documentation |
Locate the index of the first/last unique value in i) a vector or of a variable in a data frame.
## S3 method for class 'formula' firstobs(formula, data=parent.frame(), ...) ## S3 method for class 'formula' lastobs(formula, data=parent.frame(), ...) firstobs(x, ...) lastobs(x, ...)
x |
A vector |
formula |
A formula (only the first term is used, see 'details'). |
data |
A data frame |
... |
Currently not used |
If writing ~a+b+c as formula, then only a is considered.
A vector.
Søren Højsgaard, sorenh@math.aau.dk
x <- c(rep(1,5),rep(2,3),rep(3,7),rep(1,4)) firstobs(x) lastobs(x) data(dietox) firstobs(~Pig, data=dietox) lastobs(~Pig, data=dietox)