Elisabeth, You should listen to Ted (Harding). He answered your question with:
>> the vertical axis is scaled logarithmically with the >> numerical annotations corresponding to the *raw* values of Y, >> not to their log-transformed values. Therefore it does not matter >> what base of logarithms is used... And he has tried to help you further by asking you to answer the following question: >> How is it that you recognise that it is >> "a logaritmic axis with the base of 10", as opposed to any other base? Maybe a little graphic demonstration (run the script below) will help to convince you. The top row of the figure re-poses Ted's question, viz "How do you know which logarithmic base was used to plot which sub-figure?" You will see from my script that the first is plotted using natural logs, whereas the next two use logs to base 10. (The last of them uses R's log="y" argument.) What's the difference? The first two sub-figures on the bottom row show the scales that were hidden in the sub-figures above them (from the script you will see that all I did was turn off the annotation/labelling of the scale). The last sub-figure on the bottom row is identical in __appearance__ to that above it. However, as you will see from my script, it plots data that have been transformed to natural logarithms. For scale-annotation, however, I have used raw data values. That was Ted's first point: it doesn't matter which base of logarithm your data have been transformed to if you annotate the scale using (backtransformed) raw values. ## Show that log="y" does the job you want done even if internally it uses logs to the base 10 ## rather than natural logarithms par(mfrow=c(2,3)) plot(log(1:10), yaxt="n", ylab="") plot(log10(1:10), yaxt="n", ylab="") plot((1:10), log="y") plot(log(1:10)) plot(log10(1:10)) plot(log(1:10), yaxt="n") axis(side=2, at=sapply(c(1,2,5,10), FUN=function(x) log(x)), labels=c(1,2,5,10)) Regards, Mark -- View this message in context: http://r.789695.n4.nabble.com/Fwd-Re-Plotting-log-axis-with-the-exponential-base-to-a-plot-with-the-default-logarithm-base-10-tp2172435p2173481.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
