[R] basic question about changing limits on generated plots

[Jan T. Kim]

On Wed, Feb 23, 2005 at 09:14:50PM -0500, rif wrote:

> This does not do what the matlab code I posted does (the matlab code
> also works in the free program octave, if you want to try).  The
> matlab code moves already plotted data within the window (replots it).
> When I first type plot(1:10,1:10), I see a graph with axis limits [1
> 10 1 10].  When I type hold on (to keep my original data), and execute
> plot(2:12,5:15), the plot I see is equivalent to the plot I'd have
> gotten if I'd originally specified axis limits [1 12 5 15].  By
> contrast, in the R code you sent, it's as if I'm superimposing two
> unrelated plots.
> 
> Essentially, the underlying "task" is that I want to compare multiple
> functions, but I do not know good limits for the complete set of
> functions when I start.  Being able to adjust the graph to show all
> the data I've plotted so far would be extremely useful for exploratory
> analysis.  This is the mode I and colleagues generally use matlab and
> octave in.
> 
> Does this question get asked all the time?  It seems to be something
> that would come up a lot for people who switch from Matlab/Octave to
> R, but I searched the archives and didn't really see anything.

FWIW, I use constructs such as

    plotfuncs <- function(x, func, ...)
    {
      y <- as.list(1:length(func));
      for (i in 1:length(func))
      {
	y[[i]] <- sapply(x, func[[i]]);
      }
      xlim <- c(min(x), max(x));
      ylim <- c(min(sapply(y, min)), max(sapply(y, max)));
      plot.new();
      plot.window(xlim, ylim, ...);
      for (i in 1:length(func))
      {
	lines(x, y[[i]]);
      }
      axis(1, ...);
      axis(2, ...);
      box(...);
    }

    plotfuncs(1:100 / 100, list(sqrt, log, exp))

which allows you to add further functions incrementally, as in

    plotfuncs(1:100 / 100, list(sqrt, log, exp, function(x) {3 / (x + 1)}))

Perhaps, that's what you have in mind, and probably, that's what (some)
others do...

Best regards, Jan
-- 
 +- Jan T. Kim -------------------------------------------------------+
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