reorder.factor {stats}R Documentation

Reorder levels of a factor


Reorders the levels of a factor depending on values of a second variable, usually numeric.


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


x a factor (possibly ordered) 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.


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.


Deepayan Sarkar


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")

[Package stats version 2.1.0 Index]