dispersion: Display a measure of dispersion.

In plotrix/plotrix: Various Plotting Functions

Display a measure of dispersion.

Description

Display lines or capped bars at specified points on a plot representing measures of dispersion.

Usage

 dispersion(x,y,ulim,llim=ulim,intervals=TRUE,arrow.cap=0.01,arrow.gap=NA,
  type="a",fill=NA,lty=NA,pch=NA,border=NA,col=par("fg"),display.na=TRUE,
  ...)

Arguments

x,y	x and y position of the centers of the bars
ulim,llim	The extent of the dispersion measures.
arrow.cap	The width of the cap at the outer end of each bar as a proportion of the width of the plot.
arrow.gap	The gap to leave at the inner end of each bar. Defaults to two thirds of the height of a capital "O".
intervals	Whether the limits are intervals (TRUE) or absolute values (FALSE).
type	What type of display to use.
fill	Color to fill between the lines if ‘⁠type⁠’ is not NULL and ‘⁠fill⁠’ is not NA.
lty	Line type for redrawing the lines if necessary.
pch	Symbol for redrawing the points if necessary.
border	Line type for drawing a border on the confidence band.
col	Color for the lines or capped bars.
display.na	Whether to display NA values as lines going off the plot.
...	additional arguments passed to ‘⁠arrows⁠’ or ‘⁠lines⁠’ depending upon ‘⁠type⁠’.

Details

‘⁠dispersion⁠’ displays a measure of dispersion on an existing plot. Currently it will display either vertical lines with caps (error bars) or lines that form a "confidence band" around a line of central tendency. If ‘⁠fill⁠’ is not NA and ‘⁠type⁠’ is ‘⁠"l"⁠’, a polygon will be drawn between the confidence lines. Remember that any points or lines within the confidence band will be obscured, so pass point and/or line types as in the second example.

The default behavior is to display an undefined dispersion (e.g. a variance with only one observation) as a line going off the plot. If ‘⁠display.na⁠’ is FALSE, NA values will not be displayed, allowing the user to show only upper or lower dispersion limits.

The ‘⁠intervals⁠’ argument allows the user to pass the limits as either intervals (the default) or absolute values.

If ‘⁠arrow.gap⁠’ is greater than or equal to the upper or lower limit for a bar, ‘⁠segments⁠’ is used to draw the upper and lower caps with no bars to avoid zero length arrows.

Value

nil

Author(s)

Jim Lemon

See Also

arrows, segments,lines

Examples

 disptest<-matrix(rnorm(200),nrow=20)
 disptest.means<-rowMeans(disptest)
 row.order<-order(disptest.means)
 se.disptest<-unlist(apply(disptest,1,std.error))
 plot(disptest.means[row.order],main="Dispersion as error bars",
  ylim=c(min(disptest.means-se.disptest),max(disptest.means+se.disptest)),
  xlab="Occasion",ylab="Value")
 dispersion(1:20,disptest.means[row.order],se.disptest[row.order])
 plot(disptest.means[row.order],main="Dispersion as confidence band",
  ylim=c(min(disptest.means-se.disptest),max(disptest.means+se.disptest)),
  xlab="Occasion",ylab="Value")
 dispersion(1:20,disptest.means[row.order],se.disptest[row.order],type="l",
  fill="#eeccee",lty=2,pch=1)
 disptest2<-matrix(sample(c(TRUE,FALSE),200,TRUE),nrow=10)
 disptest.prop<-rowMeans(disptest2)
 disptest.ulim<-disptest.llim<-rep(NA,10)
 for(i in 1:10) {
  disptest.ulim[i]<-binciWu(disptest2[i,],20)
  disptest.llim[i]<-binciWl(disptest2[i,],20)
 }
 plot(disptest.prop,main="Dispersion as binomial confidence intervals",
  ylim=c(min(disptest.llim),max(disptest.ulim)),
  xlab="Sample",ylab="Proportion")
 dispersion(1:10,disptest.prop,disptest.ulim,disptest.llim,
  interval=FALSE,lty=2,pch=1)

plotrix/plotrix documentation built on Feb. 19, 2024, 8:16 a.m.