From: Duncan Murdoch <murdoch_at_stats.uwo.ca>

Date: Mon, 21 Jul 2008 08:43:47 -0400

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Mon 21 Jul 2008 - 12:47:11 GMT

Date: Mon, 21 Jul 2008 08:43:47 -0400

On 7/21/2008 8:13 AM, (Ted Harding) wrote:

> Hi Folks,

*> I've been digging for the solution to this for several
**> hours now. If there is a solution, it must be one of the
**> worst "needle-in-a-haystack" examples in R documentation!
**>
**> Essentially, I want to make an x-y plot in which the
**> X-axis really is the X-axis (i.e. its vertical position
**> is at y=0), and the Y-axis really is the Y-axis (i.e.
**> its horizontal position is at x=0). Discussion, with
**> toy examples, below.
**>
**> I have sort-of solved this (as stated) for one special
**> case, after a depth-4 search through
**>
**> ?plot --> ?plot.default --> ?par --> ?axis
**>
**> which finally led me to the parameter "pos" to axis():
**>
**> ?axis
**> pos: the coordinate at which the axis line is to be drawn:
**> if not 'NA' this overrides the values of both 'line' and 'mgp[3]'.
**>
**> Hence, instead of
**>
**> plot(c(0.5,2.5),c(0.5,2.5),xlim=c(0,3),ylim=c(0,3),
**> frame.plot=FALSE)
**>
**> (where the axes do not meet at the origin (0,0)), I can do
**>
**> plot(c(0.5,2.5),c(0.5,2.5),xlim=c(0,3),ylim=c(0,3),
**> frame.plot=FALSE,pos=0)
**>
**> which is *exactly* what I want in this case.
**>
**> But now I want to do the same, where instead of plotting the
**> two points (0.5,0.5), (2.5,2.5) I want to plot (0.5,2.5), (2.5,4.5).
**>
**> Provided I keep the xlim and ylim to both have lower value 0,
**> a similar solution again works fine:
**>
**> plot(c(0.5,2.5),c(2.5,4.5),xlim=c(0,3),ylim=c(0,5),
**> frame.plot=FALSE,pos=0)
**>
**> But, in this case, what I *really* want is to limit the Y range
**> to the "relevant" bit: ylim=c(2,5) -- I don't want to have a lot
**> of empty space below the points. So I want a Y-axis running from
**> y=2 to y=5, and X-axis as before from x=0 to x=3, and I want these
**> two axes to meet at (x=0,y=2). But how?
**>
**> By analogy to the above, I need to set a "pos=0" for the X-axis,
**> and a "pos=2" for the y-axis. And I have not been able to discover
**> how to do this.
*

It may or may not be possible in a single call to plot(), but it is certainly straightforward if you use separate calls to plot() and axis:

> plot(c(0.5,2.5),c(2.5,4.5),xlim=c(0,3),ylim=c(2,5), axes=F) > axis(1, pos=2) > axis(2, pos=0)

Generally speaking I find it is usually easier not to try to convince plot() to do strange things: I tell it to do nothing, and do the strange things myself.

Duncan Murdoch

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Mon 21 Jul 2008 - 12:47:11 GMT

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