[R] Contour plots

[Bill Simpson]

> I am drawing several contour plots in one page. I use "image", and get
> several contours. But I don't know how to control the color in more than one
> plots. For example, same color corresponds to different dependent values
> in different plots. For example, "yellow" means z=100(the highest value)
> in plot1, but "yellow" means z=40(the highest value) in plot2--this is
> not what I want. In fact,I want the same color corresponds the same depedent
> value in each plot. Say, in all plots, "yellow" means z=100,"red" means
> z=40, etc. I was wondering if someone can tell me which function I can
> use. Because it seems to me that "image" function doesn't have such option
> to control that.
> Thank you.

I think you need to use the zlim argument in image().

For example
image(x,y,z,zlim=c(0,100))
will make sure that all the plots are drawn using the same values for z 
(between 0 and 100 here).

Bill