R: Boxplots With Point Identification

Boxplot {car} | R Documentation

## Boxplots With Point Identification

### Description

`Boxplot` is a wrapper for the standard R `boxplot` function, providing point identification, axis labels, and a formula interface for boxplots without a grouping variable.

### Usage

    Boxplot(y, ...)

    ## Default S3 method:
    Boxplot(y, g, labels, id.method = c("y", "identify", "none"),
        id.n=10, xlab, ylab, ...)

    ## S3 method for class 'formula'
    Boxplot(formula, data = NULL, subset, na.action = NULL, labels.,
        id.method = c("y", "identify", "none"), xlab, ylab, ...)

    ## S3 method for class 'list'
    Boxplot(y, xlab="", ylab="", ...)

    ## S3 method for class 'data.frame'
    Boxplot(y, labels=rownames(y), ...)

    ## S3 method for class 'matrix'
    Boxplot(y, ...)

### Arguments

`y` | a numeric variable for which the boxplot is to be constructed; a list of numeric variables, each element of which will be treated as a group; a numeric data frame or a numeric matrix, each of whose columns will be treated as a group.
`g` | a grouping variable, usually a factor, for constructing parallel boxplots.
`labels, labels.` | point labels; if not specified, `Boxplot` will use the row names of the `data` argument, if one is given, or observation numbers, or row names if `y` is a data frame or matrix (that has row names).
`id.method` | if `"y"` (the default), all outlying points are labeled; if `"identify"`, points may be labeled interactive; if `"none"`, no point identification is performed.
`id.n` | up to `id.n` high outliers and low outliers will be identified in each group, (default, 10).
`xlab, ylab` | text labels for the horizontal and vertical axes; if missing, `Boxplot` will use the variable names, or, in the case of a list, data frame, or matrix, empty labels.
`formula` | a ‘model’ formula, of the form `~ y` to produce a boxplot for the variable `y`, or of the form `y ~ g`, `y ~ g1*g2*...`, or `y ~ g1 + g2 + ...` to produce parallel boxplots for `y` within levels of the grouping variable(s) `g`, etc., usually factors.
`data, subset, na.action` | as for statistical modeling functions (see, e.g., `lm`).
`...` | further arguments, such as `at`, to be passed to `boxplot`.

### Author(s)

John Fox jfox@mcmaster.ca, with a contribution from Steve Ellison to handle `at` argument (see `boxplot`).

### References

Fox, J. and Weisberg, S. (2011) An R Companion to Applied Regression, Second Edition, Sage.

### See Also

`boxplot`

### Examples

    Boxplot(~income, data=Prestige, id.n=Inf) # identify all outliers
    Boxplot(income ~ type, data=Prestige)
    Boxplot(income ~ type, data=Prestige, at=c(1, 3, 2))
    Boxplot(k5 + k618 ~ lfp*wc, data=Mroz)
    with(Prestige, Boxplot(income, labels=rownames(Prestige)))
    with(Prestige, Boxplot(income, type, labels=rownames(Prestige)))
    Boxplot(scale(Prestige[, 1:4]))

[Package car version 2.1-4 Index]