R help - Jun 2004 - direction of axes of plot

R users:

I want X-Y plotting with axes in reverse direction such as (0, -1, -2, -3,
....).  How can I do it?

Thanks in advance

Xiao

On Sun, 2004-06-27 at 18:24, XIAO LIU wrote:
> R users:
> 
> I want X-Y plotting with axes in reverse direction such as (0, -1, -2,
> -3, ....).  How can I do it?
> 
> Thanks in advance
> 
> Xiao
If I am understanding what you want, the following should give you an
example:

# Create x and y with negative values
x <- -1:-10
y <- -1:-10

# Show regular plot
plot(x, y)

# Now plot using -x and -y
# Do not plot the axes or annotation
plot(-x, -y, axes = FALSE, ann = FALSE)

# Now label both x and y axes with negative
# labels. Use pretty() to get standard tick mark locations
# and use rev() to create tick mark labels in reverse order
axis(1, at = pretty(-x), labels = rev(pretty(x)))
axis(2, at = pretty(-y), labels = rev(pretty(y)))

HTH,

Marc Schwartz

XIAO LIU wrote:
> R users:
> 
> I want X-Y plotting with axes in reverse direction such as (0, -1, -2, -3,
....).  How can I do it?
> 
> Thanks in advance
Use the xlim and ylim arguments to plot.

	x = -(1:10)
	y = rnorm(10)

	# Standard plot
	plot(x, y)

	# Reversed x-axis
	plot(x, y, xlim=rev(range(x)))

-- 
Ross Ihaka                         Email:  ihaka at stat.auckland.ac.nz
Department of Statistics           Phone:  (64-9) 373-7599 x 85054
University of Auckland             Fax:    (64-9) 373-7018
Private Bag 92019, Auckland
New Zealand

Assume I want to put this into a function, how do I redefine the margins 
to fit better.

I did par(mar=c(4.1,4.1,5.1,2.1) inside the function, but then it is not 
possible anymore to change them, I just want to change the default for 
this plotting function, how ?

#----------------------------------------------------------
#Function to be improved
#-----------------------------------------------------
plot.revy <- function(x,y,...)
   {
     plot(x,y,ylim=rev(range(y)),axes = FALSE,...)
     axis(2)
     axis(3)
     box()
   }

Ross Ihaka wrote:
> XIAO LIU wrote:
> 
>> R users:
>>
>> I want X-Y plotting with axes in reverse direction such as (0, -1, -2, 
>> -3, ....).  How can I do it?
>>
>> Thanks in advance
> 
> 
> Use the xlim and ylim arguments to plot.
> 
>     x = -(1:10)
>     y = rnorm(10)
> 
>     # Standard plot
>     plot(x, y)
> 
>     # Reversed x-axis
>     plot(x, y, xlim=rev(range(x)))
>

Henrik Andersson wrote:
> Assume I want to put this into a function, how do I redefine the margins 
> to fit better.
> 
> I did par(mar=c(4.1,4.1,5.1,2.1) inside the function, but then it is not 
> possible anymore to change them, I just want to change the default for 
> this plotting function, how ?
You can save the old par values and restore them
after creating your plot.

     # reset par values, saving the old ones
     oldpar = par(mar=c(4.1,4.1,5.1,2.1))

     # create stunning customized plot here

     # restore the old par values
     par(oldpar)

When embedding this in a function like yours it is better
to use the on.exit() function to restore the old values.

     f = function(...) {
         oldpar = par(mar=c(4.1,4.1,5.1,2.1))
         on.exit(par(oldpar))

         # create stunning customized plot here
     }

Error exits from the function will then also restore the old
par values.

-- 
Ross Ihaka                         Email:  ihaka at stat.auckland.ac.nz
Department of Statistics           Phone:  (64-9) 373-7599 x 85054
University of Auckland             Fax:    (64-9) 373-7018
Private Bag 92019, Auckland
New Zealand