thigmophobe.labels: Place labels away from the nearest point

In plotrix: Various Plotting Functions

Place labels away from the nearest point

Description

‘⁠thigmophobe.labels⁠’ places labels adjacent to each point, offsetting each label in the direction returned by ‘⁠thigmophobe⁠’.

Usage

 thigmophobe.labels(x,y,labels=NULL,text.pos=NULL,...)

Arguments

x,y	Numeric data vectors or a list with two components. Typically the x/y coordinates of plotted points.
labels	A vector of strings that will be placed adjacent to each point. Defaults to the indices of the coordinates.
text.pos	An optional vector of text positions (see text).
...	additional arguments are passed to ‘⁠text⁠’

.

Details

Typically used to automatically place labels on a scatterplot or similar to avoid overlapping labels. ‘⁠thigmophobe.labels⁠’ will sometimes place a label off the plot or fail to separate labels in clusters of points. The user can manually adjust the errant labels by running ‘⁠thigmophobe⁠’ first and saving the returned vector. Then modify the position values to place the labels properly and pass the edited vector to ‘⁠thigmophobe.labels⁠’ as the ‘⁠text.pos⁠’ argument. This takes precedence over the positions calculated by ‘⁠thigmophobe⁠’.

‘⁠thigmophobe⁠’ will fail with only two labels, as it can't figure out the nearest neighbors. If you really want to use this with two labels, just eyeball the plot and work out in which direction the labels will go. Then pass the directions to ‘⁠thigmophobe.labels⁠’ as the ‘⁠text.pos⁠’ argument. When all else fails, look to ‘⁠placeLabels⁠’.

Both ‘⁠pointLabel⁠’ in the maptools package and ‘⁠spread.labs⁠’ in the TeachingDemos package use more sophisticated algorithms to place the labels and are worth a try if ‘⁠thigmophobe⁠’ just won't get it right.

Value

A vector of directions away from the point nearest to each point.

Author(s)

Jim Lemon (thanks to Stephen Milborrow for finding the single point bug and Erik Aronesty for finding the two point problem.)

See Also

thigmophobe, text

Examples

 x<-rnorm(20)
 y<-rnorm(20)
 xlim<-range(x)
 xspace<-(xlim[2]-xlim[1])/20
 xlim<-c(xlim[1]-xspace,xlim[2]+xspace)
 ylim<-range(y)
 yspace<-(ylim[2]-ylim[1])/20
 ylim<-c(ylim[1]-yspace,ylim[2]+yspace)
 plotlabels<-
  c("one","two","three","four","five","six","seven","eight","nine","ten",
  "eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen",
  "eighteen","nineteen","twenty")
 plot(x=x,y=y,xlim=xlim,ylim=ylim,main="Test thigmophobe.labels")
 # skip the almost invisible yellow label, make them bold
 thigmophobe.labels(x,y,plotlabels,col=c(2:6,8:12),font=2)

plotrix documentation built on Nov. 10, 2023, 5:07 p.m.