plotrix (version 2.5-2)

barp: A bar plotting routine

Description

Display a bar plot

Usage

barp(height,width=0.4,names.arg=NULL,legend.lab=NULL,legend.pos="e",
 col=NULL,border=par("fg"),main=NULL,xlab="",ylab="",xlim=NULL,ylim=NULL,
 staxx=FALSE,staxy=FALSE, height.at=NULL,height.lab=NULL,
 cex.axis=par("cex.axis"),cylindrical=FALSE,shadow=FALSE,do.first=NULL)

Arguments

height

A numeric vector, matrix or data frame that will be represented as the heights of bars.

width

Half the width of a single bar or group of bars in X axis units.

names.arg

The labels for the bars or groups of bars.

legend.lab

Labels for an optional legend. If NULL, no legend is displayed.

legend.pos

Optional position for the legend as a list with x and y components. The default is to call emptyspace to position the legend. If this is NA, locator will be c

col

The fill colors for the bars. The default is no fill.

border

The border for the bars.

main

The title at the top of the plot.

xlab,ylab

The labels for the X and Y axes respectively.

xlim,ylim

Optional horizontal and vertical limits for the plot.

staxx,staxy

Whether to use staxlab to stagger the X or Y axis tick labels.

height.at

Optional positions of the tick marks on the Y axis.

height.lab

Optional tick labels for the Y axis.

cex.axis

Character expansion for the axis labels.

cylindrical

Whether to give the bars a cylindrical appearance by shading them.

shadow

Whether to place a shadow behind the bars.

do.first

An optional expression that will be evaluated before anything else is displayed on the plot. Useful background colors or lines.

Value

• A list containing two components of the same form as height:
• x
  The centers of the bars displayed.
• y
  The heights of the bars.

Details

barp displays a bar plot similar to barplot but with axes and horizontal bar positions more like plot. Bars or groups of bars are centered on integral X values, and so both the width and spacing of the bars are controlled by a single number. If height is a vector, single bars representing each value will be displayed centered at 1:length(height). If height is a matrix or data frame, a group of bars will be drawn for each column, with the values of the group taken from the rows of that column. The values from freq or brkdn in the prettyR package can be used as the height argument. The value from table can also be passed as height. Bars are empty by default but fill colors can be defined in several ways. If a single color is passed, all bars will be the same color. If height is a vector, colors will be recycled or some will be ignored if the length of col is not equal to that of height. If height is a matrix or data frame, the user may pass a vector of colors equal to the number of rows in height or a matrix of colors of the same dimensions as height. Other sequences of color will probably not result in an easy to interpret plot. barp is intended to simplify illustrating categorical data for which both the variable designations and the categories are names, as on many multiple choice questions. height.at and height.lab allow the user to place labels on the vertical axis, usually representing the options. If staxx or staxy are TRUE, the labels on the horizontal or vertical axes respectively will be staggered, allowing the user to use many or lengthy variable or value labels. barp allows two enhancements that may be useful in those areas where fancy plots are appreciated. One is to give the bars a cylindrical look by shading the color. The other is to place an apparent shadow behind each bar. Both of these effects appear as though the light is coming from the upper left, and this is hard coded. You can add error bars by calling dispbars, but many advise against this. If legend.lab is not NULL, a legend will be displayed. If legend.pos is NA, locator is called to place the legend. On Windows, the alert may not appear on the console, and the function will appear to hang unless the user clicks on the console window or the plot.

See Also

staxlab, barplot, cylindrect, gradient.rect

Examples

# get some extra room on the left
 par(mar=c(5,5,4,2))
 # make up some happiness data, as so many seem to do
 happyday<-data.frame(Monday=c(2.3,3.4),Tuesday=c(2.8,3.3),Wednesday=c(3.2,3.1),
 Thursday=c(3.6,2.8),Friday=c(4.2,2.6),Saturday=c(4.5,2.9),Sunday=c(4.1,2.8))
 happylabels<-c("Utterly dashed","Rather mopey","Indifferent","Somewhat elated",
  "Euphoric")
 barp(happyday,names.arg=names(happyday),legend.lab=c("Slaves","Unemployed"),
  legend.pos="e",col=c("#ee7700","#3333ff"),main="9AM happiness by weekday",
  xlab="Day of week",ylab="Happiness rating",ylim=c(1,5),staxx=TRUE,staxy=TRUE,
  height.at=1:5,height.lab=happylabels,cex.axis=0.9,cylindrical=TRUE,
  shadow=TRUE)
 # now do a plot with colors scaled to the sex ratio (real data!)
 # notice how zero and one have been added to get the full proportion range
 sexratio<-c(0,1,0.24,0.35,0.09,0.59,0.63,0.34,0.7,0.6)
 # the fun ratings are once again a pack of lies
 funrating<-c(3.2,3.5,1.5,5.4,4.5,2.7,6.8,4.9)
 funstudy<-c("Astronomy","Chemistry","Economics","Anthropology","Linguistics",
  "Math/Stats","Psychology","Sociology")
 funlabels<-c("Torture","Agony","Boredom","Neutral","Entertaining","Exhilarating",
  "Maniacal")
 # in the call to color.scale, the leading zero and one are dropped
 barp(funrating,names.arg=funstudy,main="Fun ratings for various areas of study",
  col=color.scale(sexratio[-c(1,2)],c(0.2,1),c(0.2,0.4),c(1,0.4)),xlab="Study",
  ylab="Rating",height.at=1:7,height.lab=funlabels,ylim=c(1,7),staxx=TRUE,
  staxy=TRUE,cex.axis=0.9)
 # here we want the full scale from zero to one
 color.legend(2,6,4,6.4,legend=c("100% guys","100% girls"),
  rect.col=color.scale(seq(0,1,by=0.25),c(0.2,1),c(0.2,0.4),c(1,0.4)))
 par(mar=c(5,4,4,2))