[R] quick square root axes

[Carl Witthoft]

Here's a Q&D bit of code I wrote up a while back.  Dunno if it'll be of 
any use in setting up your tickmarks.

# x, n same meaning as in pretty()
# update: check for x neg or zero
# ... is for other args to pretty()
prettylog<- function(x,n=10,base=10,...) {
	x<-unlist(x)
	if (min(x)<=0) {
		print("Warning: nonpositive values removed")
		
		x<-x[c(x>0)]
		# just to avoid a single-value fed to pretty()
		if(length(x)==1) x<-c(1,x)
		}
	return((base^(pretty(log(x,base=base),n=n,...))))
	}