psych (version 1.6.4)

densityBy: Create a 'violin plot' or density plot of the distribution of a set of variables

Description

Among the many ways to describe a data set, one is density plot or violin plot of the data. This is similar to a box plot but shows the actual distribution. Median and 25th and 75th percentile lines are added to the display. If a grouping variable is specified, densityBy will draw violin plots for each variable and for each group.

Usage

densityBy(x,grp=NULL,grp.name=NULL,ylab="Observed",xlab="",main="Density plot",density=20,
         restrict=TRUE,xlim=NULL,add=FALSE,col=NULL,pch=20, ...)
violinBy(x,grp=NULL,grp.name=NULL,ylab="Observed",xlab="",main="Density plot",density=20,
         restrict=TRUE,xlim=NULL,add=FALSE,col=NULL,pch=20, ...)

Arguments

x

A data.frame or matrix

grp

A grouping variable

grp.name

If the grouping variable is specified, the what names should be give to the group? Defaults to 1:ngrp

ylab

The y label

xlab

The x label

main

Figure title

density

How many lines per inch to draw

restrict

Restrict the density to the observed max and min of the data

xlim

if not specified, will be .5 beyond the number of variables

add

Allows overplotting

col

Allows for specification of colours. The default for 2 groups is blue and red, for more group levels, rainbows.

pch

The plot character for the mean is by default a small filled circle. To not show the mean, use pch=NA

...

Other graphic parameters

Value

• The density plot of the data.

Details

Describe the data using a violin plot. Change density to modify the shading. density=NULL will fill with col. The grp variable may be used to draw separate violin plots for each of multiple groups.

Examples

densityBy(bfi[1:5])
#not run
#violinBy(bfi[1:5],grp=bfi$gender,grp.name=c("M","F"))
#densityBy(sat.act[5:6],sat.act$education,col=rainbow(6))