[R] multhist,labels and percentages

[Federico Calboli]

On 14 May 2010, at 16:09, Thomas Stewart wrote:

> Please be more specific with your question.  Perhaps a simple subset of the data you are trying to plot?  Here is some non-specific advice:
> 
> Plotting histograms as percentages instead of frequency counts is already an option of the hist function.  For example,
> 
> pop1<-rnorm(100)
> hist(pop1,freq=F)

What you get is a desity, not a percentage, so you could have two bars with a value greater 0.5 on the y-axis. The fact that the area sums up to 1 does not mean that the sum of the heights adds up to 1 --the thing that my ignoramus want to see to understand. On the other hand, freq =T gives the counts, and the sum of the counts is the population total -- therefore (bar counts)/(pop total) *100  is the precentage. If I could slap that on the label of the y-axis I'd be sorted.

> 
> If you are plotting two histograms side-by-side (on the percentage scale), the y-axis of both plots can be set with the ylim option.  For example,
> 
> par(mfrow=c(1,2))
> pop1<-rnorm(100)
> hist(pop1,freq=F,ylim=c(0,1))
> pop2<-rgamma(100,1,1)
> hist(pop2,freq=F,ylim=c(0,1))

I'm using multhist(). The above would not work for me.

F




> 
> If your question were clearer, I might be able to help in more specific ways.
> 
> -tgs
> 
> On Fri, May 14, 2010 at 10:19 AM, Federico Calboli <f.calboli at imperial.ac.uk> wrote:
> Hi All,
> 
> I am in the annoying position of having to present some data to someone who seems to be somewhat less than numerate. I need to label the y-axes of a multhist with the y-axis labeled not as counts but as percentage of a population. Plotting the standard histogram is in a way fine, all I need is to:
> 
> -- have a left-handside y-axis labels for pop 1 and a right-handside y-axis labels for pop2
> -- replace the counts in each axis with population percentages (easy to calculate, but how to stick them there?)
> 
> Any suggestion would be gratefully received.
> 
> F
> 
> 
> --
> Federico C. F. Calboli
> Department of Epidemiology and Biostatistics
> Imperial College, St. Mary's Campus
> Norfolk Place, London W2 1PG
> 
> Tel +44 (0)20 75941602   Fax +44 (0)20 75943193
> 
> f.calboli [.a.t] imperial.ac.uk
> f.calboli [.a.t] gmail.com
> 
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--
Federico C. F. Calboli
Department of Epidemiology and Biostatistics
Imperial College, St. Mary's Campus
Norfolk Place, London W2 1PG

Tel +44 (0)20 75941602   Fax +44 (0)20 75943193

f.calboli [.a.t] imperial.ac.uk
f.calboli [.a.t] gmail.com