densityPlot {car}R Documentation

Nonparametric Density Estimates

Description

densityPlot contructs and graphs nonparametric density estimates, possibly conditioned on a factor. It is a wrapper for the standard R density function.

Usage

densityPlot(x, ...)

## Default S3 method:
densityPlot(x, g, bw = "SJ", adjust=1,
    kernel = c("gaussian", "epanechnikov", "rectangular", 
               "triangular", "biweight", "cosine", "optcosine"),
    xlab = deparse(substitute(x)), ylab = "Density", col = palette(), 
    lty = seq_along(col), lwd = 2, grid=TRUE,
    legend.location = "topright", legend.title = deparse(substitute(g)), 
    show.bw = FALSE, rug = TRUE, ...)
    
## S3 method for class 'formula'
densityPlot(formula, data = NULL, subset, na.action = NULL, xlab, ylab, ...)

Arguments

x

a numeric variable, the density of which is estimated.

g

an optional factor to divide the data.

formula

an R model formula, of the form ~ variable to estimate the unconditional density of variable, or variable ~ factor to estimate the density of variable within each level of factor.

data

an optional data frame containing the data.

subset

an optional vector defining a subset of the data.

na.action

a function to handle missing values; defaults to the value of the R na.action option, initially set to na.omit.

bw

the bandwidth for the density estimate(s); either the quoted name of a rule to compute the bandwidth, or a numeric value; the default is "SJ"; if plotting by groups, bw may be a vector of values or rules, one for each group. See density and bw.SJ for details.

adjust

a multiplicative adjustment factor for the bandwidth; the default, 1, indicates no adjustment; if plotting by groups, adjust may be a vector of adjustment factors, one for each group.

kernel

kernel function; the default is "gaussian" (see density).

xlab

label for the horizontal-axis; defaults to the name of the variable x.

ylab

label for the vertical axis; defaults to "Density".

col

vector of colors for the density estimate(s); defaults to the color palette.

lty

vector of line types for the density estimate(s); defaults to the successive integers, starting at 1.

lwd

line width for the density estimate(s); defaults to 2.

grid

if TRUE (the default), grid lines are drawn on the plot.

legend.location

location for the legend when densities are plotted for several groups; defaults to "upperright"; see legend.

legend.title

label for the legend, which is drawn if densities are plotted by groups; the default is the name of the factor g.

show.bw

if TRUE, show the bandwidth(s) in the horizontal-axis label or (for multiple groups) the legend; the default is FALSE.

rug

if TRUE (the default), draw a rug plot (one-dimentional scatterplot) at the bottom of the density estimate.

...

arguments to be passed to plot.

Value

These functions return NULL invisibly and draw graphs.

Author(s)

John Fox jfox@mcmaster.ca

References

W. N. Venables and B. D. Ripley (2002) Modern Applied Statistics with S. New York: Springer.

See Also

density, bw.SJ, link{plot.density}

Examples

densityPlot(~ income, show.bw=TRUE, data=Prestige)
densityPlot(income ~ type, data=Prestige)

[Package car version 2.0-20 Index]