densityPlot: 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, ...)
"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, ...) 
"densityPlot"(formula, data = NULL, subset, na.action = NULL, xlab, ylab, ...)

Arguments

a numeric variable, the density of which is estimated.

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.

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.

References

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

Examples

Run this code

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