[R] the title is too long for a graph
Barry Rowlingson
b.rowlingson at lancaster.ac.uk
Tue Jun 10 18:39:46 CEST 2008
Hua Li wrote:
> Hi All,
>
> I have a problem of putting long titles on a graph:
>
> for example,
>
> x= seq(1:100)
> y=seq(1:100)
> plot(x,y,main="p=0.05:A-B=3,C-D=10,D-E=100,A-F=2,AFR-E=3,ACE-D=1,ADEF-M=0,AED-E=10,DE-F=3,AB-J=4,AC-J=10,ED-F=1,ED-B=4,AF-B=10,CD-S=10,AM-C=4")
>
> R seems not able to print the whole title. The title content might be changing and thus I don't know how long it is beforehand. Is there a way to measure the length and then put the title into different lines accordingly?
>
There's a strwidth() function that gives the width of a string on the
current plot. Note you have to do the plot first so that R knows the
coordinates of the plot, since strwidth returns the width in plot
coordinates. So:
t="This is a very long title and I would like to split it somewhere, but
if I split it in the wrong place bad things will happen"
x=(1:10)*100
y=1:10
plot(x,y) # x axis is 1:1000
strwidth(t)
gives:
[1] 2002.939
but
plot(y,x) # x axis is 1:10
strwidth(t)
[1] 20.02939
Now, once you've done your plot you can get the width with:
diff(par()$usr[1:2])
[1] 9.72
and then if strwidth if your title is bigger than that you'll need to
split it into N chunks. Your splitting algorithm will have to be clever
if you want to break a sentence at word spaces though!
Hopefully this is enough to get you going.
Barry
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