densityBy {psych} R Documentation

## 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,
violinBy(x,grp=NULL,grp.name=NULL,ylab="Observed",xlab="",main="Density plot",density=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

### 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.

### Value

The density plot of the data.

None yet

William Revelle

### 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))

```

[Package psych version 1.4.5 Index]
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