xtfrm {base} | R Documentation |

## Auxiliary Function for Sorting and Ranking

### Description

A generic auxiliary function that produces a numeric vector which
will sort in the same order as `x`

.

### Usage

```
xtfrm(x)
```

### Arguments

`x` |
an |

### Details

This is a special case of ranking, but as a less general function than
`rank`

is more suitable to be made generic. The default
method is similar to ```
rank(x, ties.method = "min",
na.last = "keep")
```

, so `NA`

values are given rank `NA`

and all
tied values are given equal integer rank.

The `factor`

method extracts the codes.

The default method will unclass the object if
`is.numeric(x)`

is true but otherwise make use of
`==`

and `>`

methods for the class of `x[i]`

(for
integers `i`

), and the `is.na`

method for the class of
`x`

, but might be rather slow when doing so.

This is an internal generic primitive, so S3 or S4 methods can be written for it. Differently to other internal generics, the default method is called explicitly when no other dispatch has happened.

### Value

A numeric (usually integer) vector of the same length as `x`

.

### See Also

*base*version 4.4.0 Index]