[R] plotting gridlines

[Gavin Simpson]

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See ?grid though read the Note section of that page, which says that
more fine tuning can be achieved through the use of abline directly.

Also, note that abline is vectorized so you don't need the loop. Here is
you example, adjusted to avoid the large spaces at x and y > 9.5 and
which uses a single call to abline:

a <- runif(100)*10
b <- runif(100)*10
plot(a,b, pch=20, xlim=c(0, round(max(a))), 
     ylim=c(0, round(max(b))), type = "n")
## add 1 here to put in an extra grid line at 10
vs <- seq(0, max(a) + 1, 0.5)
hs <- seq(0, max(b) + 1, 0.5)
abline(v=vs, h=hs, col="lightgrey")
points(a, b, pch=20)

HTH

G

On Fri, 2008-01-25 at 14:14 +0100, John Lande wrote:
> dear all,
> 
> I have a very simple question but I could not figure out.
> 
> I need to make plots with grid in the background.
> 
> something like I old retrive like this
> 
> a=runif(100)*10
> b=runif(100)*10
> plot(a,b, pch=20, xlim=c(0, round(max(a))), ylim=c(0, round(max(b))))
> vs=seq(0, max(a), 0.5)
> for(i in 1:length(vs)){
>    abline(v=vs[i], col="lightgrey")
> }
> hs=seq(0, max(b), 0.5)
> for(i in 1:length(hs)){
>    abline(h=hs[i], col="lightgrey")
> }
> points(a, b, pch=20)
> 
> as you can see it is not very convenient
> 
> --
> john
> 
> 	[[alternative HTML version deleted]]
> 
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