plotrix (version 2.8-2)

hierobarp: Display a nested breakdown of numeric values.

Description

Breaks down a numeric element of a data frame by one or more categorical elements and displays the breakdown as a bar plot.

Usage

hierobarp(formula=NULL,data=NULL,maxlevels=10,mct=mean,lmd=std.error,umd=lmd,
 x=NULL,xlim=NULL,ylim=NULL,main="",xlab="",ylab="",start=0,end=1,shrink=0.02,
 errbars=FALSE,col=NA,labelcex=1,lineht=NA,showall=FALSE,barlabels=NULL,
 showbrklab=TRUE,mar=NULL,arrow.cap=0.01)

Arguments

formula

A formula with a numeric element of a data frame on the left and one or more categorical elements on the right.

data

A data frame containing the elements in formula.

maxlevels

The maximum number of levels in any categorical element. Mainly to prevent the mess caused by breaking down by a huge number of categories.

mct

The measure of central tendency function to use.

lmd

The lower measure of dispersion function to use.

umd

The upper measure of dispersion function to use.

x

This becomes the result of the breakdown after the first call. If a list of arrays of values of the same form as that produced by hierobrk is passed, it will be used to determine the heights of the nested bars.

xlim,ylim

Optional x and y limits for the plot.

main

Title for the plot.

xlab,ylab

Axis labels for the plot.

start,end

The start and end values of the initial display. The user will almost certainly not want to change these.

shrink

The proportion to shrink the width of the bars as more levels are added. This proportion increases with the number of levels.

errbars

Whether to display error bars on the lowest level of breakdown.

col

The colors to use to fill the bars. See Details.

barlabels

Optional group labels that may be useful if the factors used to break down the numeric variable are fairly long strings.

labelcex

Character size for the group labels.

lineht

The height of a line of text in the lower margin of the plot in user units. This will be calculated by the function if a value is not passed.

showall

Whether to display bars for the entire breakdown.

showbrklab

Whether to display the labels for the lowest level of breakdown.

mar

If not NULL, a four element vector to set the plot margins. If new margins are set, the user must reset the margins after the function exits.

arrow.cap

The width of the "cap" on error bars in user units, defaulting to 0.01.

Value

• The summary arrays produced by hierobrk.

Details

hierobarp displays a bar plot illustrating the breakdown of a numeric element of a data frame by one or more categorical elements. The breakdown is performed by hierobrk. Typically, the mean of each category specified by the formula is displayed as the height of a bar. If showall is TRUE, the entire nested breakdown will be displayed. This can be useful in visualizing the relationship between groups and subgroups in a compact format.

The colors of the bars are determined by col. If showall is FALSE, the user only need pass a vector of colors, usually the same length as the number of categories in the final (first on the right side) element in the formula. If showall is TRUE and the user wants to color all of the bars, a list with as many elements as there are levels in the breakdown should be passed. Each element should be a vector of colors, again usually the same length as the number of categories. As the categorical variables are likely to be factors, it is important to remember that the colors must be in the correct order for the levels of the factors. When the levels are not in the default alphanumeric order, it is quite easy to get this wrong.

See Also

hierobrk, barp

Examples

test.df<-data.frame(Age=rnorm(100,25,10),
  Sex=sample(c("M","F"),100,TRUE),
  Marital=sample(c("D","M","S","W"),100,TRUE),
  Employ=sample(c("Full Time","Part Time","Unemployed"),100,TRUE))
 test.col<-list(Overall="gray",Employ=c("#1affd8","#caeecc","#f7b3cc"),
  Marital=c("mediumpurple","orange","tan","lightgreen"),Sex=c("pink","lightblue"))
 hierobarp(formula=Age~Sex+Marital+Employ,data=test.df,ylab="Mean age (years)",
  main="Show only the final breakdown",errbars=TRUE,col=test.col$Sex)
 # set up functions for 20 and 80 percentiles - must be offsets, not limits
 q20<-function(x,na.rm=TRUE) return(mean(x)-quantile(x,probs=0.2,na.rm=TRUE))
 q80<-function(x,na.rm=TRUE) return(quantile(x,probs=0.8,na.rm=TRUE)-mean(x))
 # show the asymmetric dispersion measures
 hierobarp(formula=Age~Sex+Marital+Employ,data=test.df,ylab="Mean age (years)",
  main="Use median and quantiles for dispersion",mct=median,lmd=q20,umd=q80,
  errbars=TRUE,col=test.col$Sex)
 # start a wide plot window for this one
  x11(width=10)
  hierobarp(formula=Age~Sex+Marital+Employ,data=test.df,ylab="Mean age (years)",
   main="Show the entire hierarchical breakdown",col=test.col,showall=TRUE,
   showbrklab=TRUE,mar=c(5,4,4,8))
  # example of a legend that might be included, needs a lot of space
  par(xpd=TRUE)
  legend(1.02,27,c("Overall","Full time","Part time","No work","Divorced",
   "Married","Single","Widowed","Female","Male"),
   fill=unlist(test.col))
  par(xpd=FALSE,mar=c(5,4,4,2))