```
# color a random walk "hot" (red) to "cold" (blue) on its distance
# from the starting point
x<-c(0,cumsum(rnorm(99)))
y<-c(0,cumsum(rnorm(99)))
xydist<-sqrt(x*x+y*y)
plot(x,y,main="Random walk plot",xlab="X",ylab="Y",type="n")
color.scale.lines(x,y,c(1,1,0),0,c(0,1,1),colvar=xydist,lwd=2)
boxed.labels(x,y,labels=1:100,border=FALSE,cex=0.5)
# now color the lines to show whether each step went away from
# or toward the starting position
color.scale.lines(x,y,col=2+(diff(xydist)>0))
boxed.labels(x,y,labels=1:100,border=FALSE,cex=0.5)
```

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