Labelling logarithmic scale display in R Labelling logarithmic scale display in R r r

Labelling logarithmic scale display in R


Apart from the solution of ggplot2 (see gsk3's comment), I would like to add that this happens automatically in plot() as well when using the correct arguments, eg :

x <- 1:10y <- exp(1:10)plot(x,y,log="y")

You can use the parameter log="x" for the X axis, or log="xy" for both.

If you want to format the numbers, or you have the data in log format, you can do a workaround using axis(). Some interesting functions :

  • axTicks(x) gives you the location of the ticks on the X-axis (x=1) or Y-axis (x=2)
  • bquote() converts expressions to language, but can replace a variable with its value. More information on bquote() in the question Latex and variables in plot label in R? .
  • as.expression() makes the language object coming from bquote() an expression. This allows axis() to do the formatting as explained in ?plotmath. It can't do so with language objects.

An example for nice formatting :

x <- y <- 1:10plot(x,y,yaxt="n")aty <- axTicks(2)labels <- sapply(aty,function(i)            as.expression(bquote(10^ .(i)))          )axis(2,at=aty,labels=labels)

Which gives

enter image description here


Here is a different way to draw this type of axis:

plot(NA, xlim=c(0,10), ylim=c(1, 10^4), xlab="x", ylab="y", log="y", yaxt="n")at.y <- outer(1:9, 10^(0:4))lab.y <- ifelse(log10(at.y) %% 1 == 0, at.y, NA)axis(2, at=at.y, labels=lab.y, las=1)

enter image description here

EDIT: This is also solved in latticeExtra with scale.components


In ggplot2 you just can add a

... + scale_x_log10() + scale_y_log10(limits = c(1e-4,1), breaks=c(1e-4,1e-3,1e-2,0.1,1)) + ...

to scale your axis, Label them and add custom breaks.