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

firstlastobs {doBy} | R Documentation

## 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

    lastobs(x, ...)

    firstobs(x, ...)

    ## Default S3 method:
    lastobs(x, ...)

    ## Default S3 method:
    firstobs(x, ...)

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

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

### Arguments

`x` | A vector
`...` | Currently not used
`formula` | A formula (only the first term is used, see 'details').
`data` | A data frame

### Details

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

### Value

A vector.

### Author(s)

Søren Højsgaard, sorenh@math.aau.dk

### 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)

[Package doBy version 4.6.5 Index]