reorder.factor {stats}

R Documentation

Reorder Levels of a Factor

Description

reorder is a generic function. Its "factor" method reorders the levels of a factor depending on values of a second variable, usually numeric. The "character" method is a convenient alias.

Usage

reorder(x, ...)

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

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

Arguments

x	a character vector or factor (possibly ordered) or whose levels will be reordered.
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.

Value

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.

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.

Author(s)

Deepayan Sarkar deepayan.sarkar@r-project.org

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")

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