quick square root axes

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Dear R users,
while I enjoy the built-in log argument to the plot() function, I wished it
would be as easy to create more general custom transformed axes such as
sqrt(), logit, etc...

for example, instead of
 plot(x=exp(rnorm(10)), y=(1:10)^4, log = "xy"), sth. along the lines of
 plot(x=exp(rnorm(10)), y=(1:10)^4, trans = list(x = log, y = sqrt))
to encode the desired transfomation.

This involves just transforming the xy values and creating nice tick marks
at the appropriate positions.
Before trying to write my own function, I wanted to see if that
functionality already exists in another package ?
I don't know of such a thing, but it may well exist.

If you do write your own, the hardest part will be picking the nice tick 
marks.  They should be approximately evenly spaced, but at nice round 
values of the original variable:  that's hard to do in general.  R has 
the pretty() function for the linear scale, and doesn't do too badly on 
log axes, but you'll need to work out your own rules for the sqrt or 
other scales.

Duncan Murdoch

On 5/5/2009 1:05 PM, Markus Loecher wrote:
Dear R users,
while I enjoy the built-in log argument to the plot() function, I  
wished it
would be as easy to create more general custom transformed axes  
such as
sqrt(), logit, etc...

for example, instead of
plot(x=exp(rnorm(10)), y=(1:10)^4, log = "xy"), sth. along the  
lines of
plot(x=exp(rnorm(10)), y=(1:10)^4, trans = list(x = log, y = sqrt))
to encode the desired transfomation.

This involves just transforming the xy values and creating nice  
tick marks
at the appropriate positions.
Before trying to write my own function, I wanted to see if that
functionality already exists in another package ?

Have you tried ggplot2? I think Hadley has given a lot of thinking on  
this sort of issues.

http://had.co.nz/ggplot2/
http://had.co.nz/ggplot2/coord_trans.html

baptiste
I don't know of such a thing, but it may well exist.

If you do write your own, the hardest part will be picking the nice  
tick
marks.  They should be approximately evenly spaced, but at nice round
values of the original variable:  that's hard to do in general.  R has
the pretty() function for the linear scale, and doesn't do too badly  
on
log axes, but you'll need to work out your own rules for the sqrt or
other scales.

Duncan Murdoch

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Baptiste Augui?

School of Physics
University of Exeter
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EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag
If you do write your own, the hardest part will be picking the nice tick
marks. ?They should be approximately evenly spaced, but at nice round values
of the original variable: ?that's hard to do in general. ?R has the pretty()
function for the linear scale, and doesn't do too badly on log axes, but
you'll need to work out your own rules for the sqrt or other scales.
This seems like a nice (if smallish) research problem...

Hadley
http://had.co.nz/
Dear R users,
while I enjoy the built-in log argument to the plot() function, I wished it
would be as easy to create more general custom transformed axes such as
sqrt(), logit, etc...

for example, instead of
 plot(x=exp(rnorm(10)), y=(1:10)^4, log = "xy"), sth. along the lines of
 plot(x=exp(rnorm(10)), y=(1:10)^4, trans = list(x = log, y = sqrt))
to encode the desired transfomation.

This involves just transforming the xy values and creating nice tick marks
at the appropriate positions.
Before trying to write my own function, I wanted to see if that
functionality already exists in another package ?

Hi Markus,
The axis.mult function in plotrix does this for linear multipliers, but 
a more general transformation is a bit harder. I'll have a look at the 
log axis transformation and scratch my head a bit.

Jim