[R] controlling plot range
Marc Schwartz
marc_schwartz at comcast.net
Fri Oct 19 20:04:44 CEST 2007
Bert et al,
A point of clarification. If one reads ?par, one will note [emphasis
added]:
There are several parameters can **only** be set by a call to par():
* "ask",
* "fig", "fin",
* "lheight",
* "mai", "mar", "mex", "mfcol", "mfrow", "mfg",
* "new",
* "oma", "omd", "omi",
* "pin", "plt", "ps", "pty",
* "usr",
* "xlog", "ylog"
The remaining parameters can also be set as arguments (often via ...) to
high-level plot functions such as ...
Thus, par("usr") at least by documentation, cannot be set using it
'inline' in a plot function call as John has attempted here.
HTH,
Marc Schwartz
On Fri, 2007-10-19 at 10:49 -0700, Bert Gunter wrote:
> John:
>
> I agree: the Docs are not clear on this. V&R's MASS (p.84 in the 4th
> edition) gives an explanation:
>
> "Positions in the plot region may also be specified in absolute **user
> coordinates**. Initially user coordinates and relative coordinates
> [..relative to the unit square of the enclosing region--BG] coincide,, but
> any high-level plotting function changes the user coordinates so that the x-
> and y- coordinates range from their minimum to maximum values as given by
> the plot axes."
>
> As James said, xlim and ylim is what you want. A more extensive discussion
> and examples of the use of usr coordinates can be found in Paul Murrell's R
> GRAPHICS book, pp. 99 -105.
>
> Bert Gunter
> Genentech Nonclinical Statistics
>
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
> Behalf Of James
> Sent: Friday, October 19, 2007 10:01 AM
> To: John Sorkin
> Cc: r-help at r-project.org
> Subject: Re: [R] controlling plot range
>
> On Oct 19, 2007, at 10:54 AM, John Sorkin wrote:
>
> > Windows XP
> > R 2.5.0
> > I am trying to produce two plots that have the same range, i.e. x
> > from 50 to 400 on both plots and y from 50 to 400 on both plots.
> > (This will allow me to compare slopes). I have used the code below
> > without success using usr (I have also used xaxp and yaxp but I am
> > not including the code):
> >
> > plot(tgNo26[,"TGh"],tgNo26[,"TGs"],usr=c(50,400,50,400))
> > plot(tgNo26[grep("CONTROL",tgNo26[,"PATIENT"]),"TGh"],
> > tgNo26[grep("CONTROL",tgNo26[,"PATIENT"]),"TGs"],usr=c
> > (50,400,50,400))
> >
> > RESULT:
> > axes on first plot 50-400, y axis 50-350
> > axes on second plot 50-250 y axis 100-250
>
> From
>
> ?plot.default
>
> Are you looking for:
>
> xlim the x limits (x1, x2) of the plot. Note that x1 > x2 is
> allowed
> and leads to a "reversed axis".
> ylim the y limits of the plot.
>
> I believe this will allow you to set the axes to the same limits so
> that you can compare more easily.
>
> HTH
>
> James
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