[R] the title is too long for a graph

[Barry Rowlingson]

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