On 09/12/2013 03:51 AM, isabe...@ghement.ca wrote:
BODY { font-family:Arial, Helvetica, sans-serif;font-size:12px;
}Hello,
I am trying to create a plot whose x-axis is wide enough to
accommodate the following:
a) a character string on the left side (i.e., Text 1);
b) a known range of values in the middle (i.e., Range);
c) a character string on the right side (i.e., Label 2)
The plot would start with the range of values in the middle and would
be expanded to the left and right by a width proportional to the
length of Text 1 and Label 2, respectively. (The width would need to
be expressed in the same units as those of the middle range of
values.)
In R, how can I determine the width of Text 1 and Label 2 and express
it in the same units as those pertaining to Range? (I know how to
determine the width of these character strings in inches for a given
plot via strwidth(), but for some reason I am not able to connect that
width to the units of Range.)
Here is some R code illustrating what the plot would look like:
plot(NA, xlim=c(1,10), ylim=c(1,5),type="N")
abline(v=1,lty=2,col="red")
abline(v=2,lty=2,col="red")
abline(v=8,lty=3,col="blue")
abline(v=10,lty=3,col="blue")
text(1,3,"Text 1",pos=4)
text(8,3,"Label 2",pos=4)
arrows(2,3,8,3,code=3, length=0.1,lwd=2)
text(5,3,"Range",pos=3)
Hi Isabella,
Your illustration is helpful, but there are a couple of things that I
will have to guess. The first is that you want the usual margins around
the plot, and the second is that the outer vertical lines on your
illustration are the "x" limits {par(usr[1:2])} of the plot. What you
have is a fairly simple algebra problem.
xrange = stringwidth1 + xlim + stringwidth2
Using the default plotting device on my setup:
xrange = 5.76 in.
stringwidth1 = 0.457 in.
stringwidth2 = 0.551 in.
Therefore xlim must fit into:
5.76 - 1.008 = 4.75 in.
Say your xlim (in user units) is 1 to 10. This means that the xlim
passed to the plot command must be:
10 * 5.76/4.75 = 12.13
or if you want the default .04 padding on either side:
10.08 * 5.76/4.75 = 12.23
Having discovered this, you can now plot with:
xlim<-c(1 - 2.13 * 0.457/1.008,10 + 2.13 * 0.551/1.008)
plot(1:10,1:10,xlim=xlim,xaxt="n")
axis(1,at=1:10)
text(xlim[1],5,"Text 1")
text(xlim[2],5,"Label 2",adj=1)
So in general, plot without the strings with the full x range, then
adjust for the strings, then plot again.
You will probably want to fiddle with the padding and text adjustments.
Jim
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