R help - Jul 2006 - Misunderstanding with lines (or elsewhere)

Misunderstanding with lines(...) :
http://7d4.com/r/

I would like the y coordinate of the horizontal line to be 1/4,
and also the line to begin at x=0 and end at y=1.

I'm obviously missing something
... so if anybody could help.

Many thanks.


test = function()
{
bmp('test.bmp', width=100, height=100)
m = matrix(0, 2, 2)
par(new=T, fig = c(0,1,0,1), mai=c(0,0,0,0), mar=c(0,0,0,0), bty='n')
image(m)
lines(c(0,1), c(1/4,1/4))         # horizontal line
a = dev.off()
}


The result :
http://7d4.com/r/

Think about the coordinate system you are using: if you don't set the 
margins to zero you will see what it is.

I suggest you supply x and y to image() to set the coordinate system to 
what you want it to be.

On Tue, 11 Jul 2006, vincent at 7d4.com wrote:
> Misunderstanding with lines(...) :
> http://7d4.com/r/
> 
> I would like the y coordinate of the horizontal line to be 1/4,
> and also the line to begin at x=0 and end at y=1.
And that is what you get.
> I'm obviously missing something
> ... so if anybody could help.
> 
> Many thanks.
> 
> 
> test = function()
> {
> bmp('test.bmp', width=100, height=100)
> m = matrix(0, 2, 2)
> par(new=T, fig = c(0,1,0,1), mai=c(0,0,0,0), mar=c(0,0,0,0),
bty='n')
> image(m)
> lines(c(0,1), c(1/4,1/4))         # horizontal line
> a = dev.off()
> }
> 
> 
> The result :
> http://7d4.com/r/
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
> 
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595