quick square root axes
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 ?
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