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# reorder.default {stats}

Reorder Levels of a Factor
Package:
stats
Version:
R 3.0.2

### Description

`reorder` is a generic function. The `"default"` method treats its first argument as a categorical variable, and reorders its levels based on the values of a second variable, usually numeric.

### Usage

```reorder(x, ...)

## S3 method for class 'default':
reorder((x, X, FUN = mean, ...,
order = is.ordered(x)))

```

### Arguments

x
An atomic vector, usually a factor (possibly ordered). The vector is treated as a categorical variable whose levels will be reordered. If `x` is not a factor, its unique values will be used as the implicit levels.
X
a vector of the same length as `x`, whose subset of values for each unique level of `x` determines the eventual order of that level.
FUN
a function whose first argument is a vector and returns a scalar, to be applied to each subset of `X` determined by the levels of `x`.
...
optional: extra arguments supplied to `FUN`
order
logical, whether return value will be an ordered factor rather than a factor.

### Values

A factor or an ordered factor (depending on the value of `order`), with the order of the levels determined by `FUN` applied to `X` grouped by `x`. The levels are ordered such that the values returned by `FUN` are in increasing order. Empty levels will be dropped.

Additionally, the values of `FUN` applied to the subsets of `X` (in the original order of the levels of `x`) is returned as the `"scores"` attribute.

### See Also

`reorder.dendrogram`, `levels`, `relevel`.

### Examples

```require(graphics)

bymedian <- with(InsectSprays, reorder(spray, count, median))
boxplot(count ~ bymedian, data = InsectSprays,
xlab = "Type of spray", ylab = "Insect count",
main = "InsectSprays data", varwidth = TRUE,
col = "lightgray")```

### Author(s)

Deepayan Sarkar deepayan.sarkar@r-project.org

Documentation reproduced from R 3.0.2. License: GPL-2.