[R] Boxplot with Log10 and base-exponent axis

[William Dunlap]

To change the y-limits you need to add ylim=c(min,max)
to the call to boxplot.  The limits there should be
in the units of the y variable (not its log10).  par("usr")[3:4]
report the y-limits on the log10 scale (they will be expanded
a bit from your desired limits so the plot does not extend
all the way to edge).

> boxplot(abs(tan(1:100)), log="y", ylim=c(.001, 1000))
> par("usr")[3:4]
[1] -3.24  3.24
> 10 ^ par("usr")[3:4]
[1] 5.754399e-04 1.737801e+03

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 

> -----Original Message-----
> From: Luigi [mailto:marongiu.luigi at gmail.com]
> Sent: Saturday, June 23, 2012 8:49 AM
> To: William Dunlap
> Cc: 'Martin Maechler'; r-help at r-project.org
> Subject: RE: [R] Boxplot with Log10 and base-exponent axis
> 
> Thank you!
> This works good. I understand that the value are now in Log10 scale,
> although I did not understand what is happening  at line 4 of your script.
> I would like to ask how can I change the y limits since they now depend on
> par("user"). What if I'd like y limits extending from 1000 to 1 000 000?
> I've tried to modify ylim (line 3) and ceiling (line 4) but I obtained
> errors.
> Best wishes,
> Luigi
> 
> 
> ############### UPDATED EXAMPLE ############################################
> # generationg random numbers
> 	x<-runif(100, min=0, max=100000)
> 
> 
> #plotting
> 	boxplot(x, log = "y", yaxt="n")
>   	 ylim <- par("usr")[3:4]
> 
> 	log10AtY <- seq(ceiling(ylim[1]), floor(ylim[2]))
> 
>   	axis(side=2, at=10^log10AtY, lab=as.expression(lapply(log10AtY,
> function(y)bquote(10^.(y)))))
> 
> ############################################################################
> #
> 
> 
> ------------------ Your Response
> --------------------------------------------
> The key is to supply an expression, not text, to the labels argument to
> axis.
> See help("plotmath") for details.  Here is an example:
> 1  x <- list(One=10^(sin(1:10)+5), Two=10^(cos(1:30)*2))
> 2  boxplot(x, log="y", yaxt="n")
> 3  ylim <- par("usr")[3:4]
> 4  log10AtY <- seq(ceiling(ylim[1]), floor(ylim[2]))
> 5  axis(side=2, at=10^log10AtY, lab=as.expression(lapply(log10AtY,
> function(y)bquote(10^.(y)))))
> 
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com
> 
> > -----Original Message-----
> > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> On Behalf
> > Of Luigi
> > Sent: Friday, June 22, 2012 7:54 AM
> > To: r-help at r-project.org
> > Subject: [R] Boxplot with Log10 and base-exponent axis
> >
> > Dear all,
> >
> > I would like to (i) produce boxplot graphs with axis in logarithm in base
> 10
> > and (ii) showing the values on the axis in 10^exponent format rather than
> > 10E+exponent.
> >
> >
> >
> > To illustrate with an example, I have some widely spread data that I chart
> > plot using  boxplot() [figure on the left]; the log="y" option of
> boxplot()
> > I obtained the natural logarithm conversion of the data and the unfriendly
> > notation baseE+exponent [figure on the centre]; if I log10 the data I
> obtain
> > the desired plot, but the axis are showing only the exponent. [figure on
> the
> > right].
> >
> >
> >
> > Can anybody help?
> >
> >
> >
> > Best regards
> >
> > Luigi Marongiu, MSc
> >
> >
> >
> > ########### EXAMPLE ############
> >
> > # generationg random numbers
> >
> > x<-runif(100, min=0, max=100000)
> >
> >
> >
> > # create plot
> >
> > par(mfrow = c(1,3))
> >
> >
> >
> > #plotting in the left side
> >
> > boxplot(x, xlab="Linear values")
> >
> >
> >
> > #plotting in the centre
> >
> > boxplot(x, log = "y", xlab="y axis logged")
> >
> >
> >
> > # creating log10 values and plotting on the right side
> >
> > Log.base10.x<-log10(x)
> >
> > boxplot(Log.base10.x, xlab="LOG10 of data")
> >
> >
> >
> >
> >
> >
> > 	[[alternative HTML version deleted]]
> >
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