[R] How to change min and max of plot axis

[Marc Schwartz]

on 06/21/2008 10:25 AM Luis Orlindo Tedeschi wrote:
> All; this might be an easy question but I cannot make it work. I would
> like to set the min and max of the y axis of a plot. I know I have to
> use par("usr"), but after I do the plot() the axis values get changed.
> 
> x<-rnorm(20)
> Y<-x+rnorm(20,0,.1)
> plot(y,x)
> par("usr")
> 
> # let's say I have -2.8 1.15 -2.8 1.16 for par("usr")
> # let's say I need to change the Y-axis to be -5 to 5
> 
> usr<-par("usr")
> par(usr=c(usr[1:2],-5,5))
> plot(y,x)
> 
> # it does not take the -5 to 5???
> 
> Is there any way to set the axis values?
> 
> Thanks

In ?par, take note of the 'ylim' and 'xlim' parameters, which are also 
noted in ?plot.default.

  x <- rnorm(20)
  y <- x + rnorm(20, 0, .1)
  plot(x, y, ylim = c(-5, 5))

HTH,

Marc SChwartz