R: Determine all duplicate elements

duplicated2 {questionr} | R Documentation

## Determine all duplicate elements

### Description

The native duplicated function determines which elements of a vector or data frame are duplicates of elements already observed in the vector or the data frame provided. Therefore, only the second occurence (or third or nth) of an element is considered as a duplicate. `duplicated2` is similar but will also mark the first occurence as a duplicate (see examples).

### Usage

    duplicated2(x)

### Arguments

`x` | a vector, a data frame or a matrix

### Value

A logical vector indicated wich elements are duplicated in `x`.

### Source

http://forums.cirad.fr/logiciel-R/viewtopic.php?p=2968

### See Also

duplicated

### Examples

    df <- data.frame(x=c("a","b","c","b","d","c"),y=c(1,2,3,2,4,3))
    df
    duplicated(df)
    duplicated2(df)

[Package questionr version 0.6.3 Index]