R help - Feb 2004 - suppressing non-integer labels for plot x-axis

Jonathan Williams wrote:
> I am having difficulty making R plot only integer labels on the x-axis
> of a simple graph. I want to plot the median values of a score on each
> of three occasions. Non-integer occasions are impossible. But, R keeps
> labelling the x-axis with half-occasions, despite my attempts to stop
> this using the "xaxs" and "xaxp" parameters of
'plot'.
> 
> p1=c(1,2,3); p2=c(5,15,25)
> plot(p1,p2,xlab='Occasion', ylab='Score', xlim=c(1,3),
ylim=c(0,30),
> xaxp=c(1,3,3), xaxs='r')
> 
> Could someone let me know how to suppress the non-integer labels?
How about this instead?

plot(p1, p2, xlab='Occasion', ylab='Score', xlim=c(1,3),
ylim=c(0,30),
xaxt="n")

axis(side=1, at=1:3, 1:3)

-- 
Chuck Cleland, Ph.D.
NDRI, Inc.
71 West 23rd Street, 8th floor
New York, NY 10010
tel: (212) 845-4495 (Tu, Th)
tel: (732) 452-1424 (M, W, F)
fax: (917) 438-0894

Dear R-helpers,
I am having difficulty making R plot only integer labels on the x-axis
of a simple graph. I want to plot the median values of a score on each
of three occasions. Non-integer occasions are impossible. But, R keeps
labelling the x-axis with half-occasions, despite my attempts to stop
this using the "xaxs" and "xaxp" parameters of
'plot'.

p1=c(1,2,3); p2=c(5,15,25)
plot(p1,p2,xlab='Occasion', ylab='Score', xlim=c(1,3),
ylim=c(0,30),
xaxp=c(1,3,3), xaxs='r')

Could someone let me know how to suppress the non-integer labels?

Thanks

Jonathan Williams
OPTIMA
Radcliffe Infirmary
Woodstock Road
OXFORD OX2 6HE
Tel +1865 (2)24356

Jonathan Williams wrote:
> Dear R-helpers,
> I am having difficulty making R plot only integer labels on the x-axis
> of a simple graph. I want to plot the median values of a score on each
> of three occasions. Non-integer occasions are impossible. But, R keeps
> labelling the x-axis with half-occasions, despite my attempts to stop
> this using the "xaxs" and "xaxp" parameters of
'plot'.
> 
> p1=c(1,2,3); p2=c(5,15,25)
> plot(p1,p2,xlab='Occasion', ylab='Score', xlim=c(1,3),
ylim=c(0,30),
> xaxp=c(1,3,3), xaxs='r')
> 
> Could someone let me know how to suppress the non-integer labels?
In this case supress the drawing of the x-axis and specify it 
explicitly, see ?axis:

plot(p1, p2, xlab='Occasion', ylab='Score', xlim=c(1,3),
ylim=c(0,30),
xaxt="n")
axis(1, at=1:3)

Uwe Ligges

On Thu, 2004-02-19 at 07:20, Jonathan Williams wrote:
> Dear R-helpers,
> I am having difficulty making R plot only integer labels on the x-axis
> of a simple graph. I want to plot the median values of a score on each
> of three occasions. Non-integer occasions are impossible. But, R keeps
> labelling the x-axis with half-occasions, despite my attempts to stop
> this using the "xaxs" and "xaxp" parameters of
'plot'.
> 
> p1=c(1,2,3); p2=c(5,15,25)
> plot(p1,p2,xlab='Occasion', ylab='Score', xlim=c(1,3),
ylim=c(0,30),
> xaxp=c(1,3,3), xaxs='r')
> 
> Could someone let me know how to suppress the non-integer labels?

If you want finer control over the axis labeling, it is generally best
to suppress the axis or axes in question and explicitly draw the axis
using the axis() function.

By default, the tick marks and labels will be the result of using the
pretty() function, based upon the range of values you provide. Thus you
get:
> pretty(1:3)
[1] 1.0 1.5 2.0 2.5 3.0


To avoid this and have more control, do something like:

p1=c(1, 2, 3)
p2=c(5, 15, 25)

# Use 'xaxt = "n"' to suppress the x axis
plot(p1, p2, xlab = 'Occasion', ylab = 'Score',
     xlim = c(1, 3), ylim = c(0, 30), xaxt = "n")

# Now call axis to draw tick marks and labels at 1:3
axis(1, at = 1:3)

See ?pretty, ?plot.default and ?axis for more information.

HTH,

Marc Schartz