PlotConDens: Plot Conditional Densities

Description

Plot conditional densities by group. For describing how the conditional distribution of a categorical variable y changes over a numerical variable x we have the function cdplot. But if we want to compare multiple densities much work is required. PlotConDens allows to easily enter a grouping variable.

Usage

PlotConDens(formula, data, col = NULL, lwd = 2, lty = 1, xlim = NULL, rev = TRUE, 
            args.dens = NULL, ...)

Value

the functions for the curves

Arguments

formula: a "formula" of type y ~ x | g with a single dependent factor, a single numerical explanatory variable and a grouping factor g.
data: a data frame containing values for any variables in the formula. By default the environment where PlotConDens was called from is used.
col: a vector of colors to be used to plot the lines. If too short, the values are recycled.
lwd: a vector of linewidths to be used to plot the lines. If too short, the values are recycled.
lty: a vector of linetypes to be used to plot the lines. If too short, the values are recycled.
xlim: the range for the x axis.
rev: logical, should the values of the response variable be reversed? Default is TRUE.
args.dens: additional arguments for the densitiy curves.
...: the dots are passed on to plot().

Author

Andri Signorell <andri@signorell.net>

Details

Especially when we're modelling binary response variables we might want to know, how the binary variable behaves along some numeric predictors.

Examples

Run this code

data(Pima.tr2, package="MASS")
PlotConDens (type ~ age | I((npreg > 0)*1L), 
             data=Pima.tr2, col=c(hblue, hred), rev=FALSE, 
             panel.first=quote(grid()))

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