[R] two y-axis using ggplot

[Ben Bolker]

Thorsten Vogel <thorsten.vogel <at> staff.hu-berlin.de> writes:
> Dear List Members
> 
> As a relatively new R user I am extremely glad for there being a nice 
> tool such as ggplot for producing easily nice graphs in R. Now I want to 
> produce graphs with two y-axis. I know that this has been asked a 
> hundred times with respect to standard plots in R. (The answer, to my 
> knowledge, has always been "No" or "No, see the help archive".) But: Is 
> there a more straightforward way IN GGPLOT to draw several lines in one 
> graphs using two different scales and displaying these two scales on the 
> y-axis and the, say, z-axis? Seems to be an obvious extensions of 
> typical plot commands but I can't find any suggestions how to do it.
> 
> Many thanks for any suggestions or hints.
> 
> Best,
> Thorsten

  Don't know the answer for ggplot, but just for the
record: the answer to the basic-plot question is
"(1) not automatically in base R; (2) see the R wiki
for commands to do this in base R without two much
trouble; (3) see twoord.plot in the plotrix package;
(4) there are lots of good reasons not to do this
(again see the R wiki)."

  cheers
   Ben Bolker