doBy (version 3.9)

firstlastobs: Locate the index of the first/last unique value

Description

Locate the index of the first/last unique value in i) a vector or of a variable in a data frame.

Usage

## S3 method for class 'formula':
firstobs(formula, data=parent.frame(), ...)
## S3 method for class 'formula':
lastobs(formula, data=parent.frame(), ...)
firstobs(x, ...)
lastobs(x, ...)

Arguments

x

A vector

formula

A formula (only the first term is used, see 'details').

data

A data frame

...

Currently not used

Value

• A vector.

Details

If writing ~a+b+c as formula, then only a is considered.

Examples

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)