Dear Ben,

thank you very much for your prompt reply.

but I'm afraid I'm missing something: when I apply your function pmulthist I
obtain exactly the same results as with multhist (with the y axis
representing frequencies rather than a probability).

I was checking but couldn't find the problem (*"allhist" is clearly set to
be freq=False*)

I would appreciate a lot if you can point out what I'm missing.

Ahimsa

# This is what I do:

library(plotrix)

pmulthist <-
function (x, breaks = "Sturges", ...)
{
   allhist <- hist(unlist(x), breaks = breaks, plot = FALSE, freq=FALSE)
   combhist <- t(sapply(x, function(z) hist(z, breaks = allhist$breaks,
       plot = FALSE)$counts))
   barplot(combhist, beside = TRUE, names = signif(allhist$mids,
       2), ...)
}

mh <- list(rnorm(200, mean=200, sd=50), rnorm(200, mean=250, sd=50))

pmulthist(mh)
# y-axis appears as frequency values

multhist(mh)
# the histogram is identical to previous



On 11/30/06, Ben Bolker <bolker@zoo.ufl.edu> wrote:
>
> ahimsa campos-arceiz <ahimsa <at> camposarceiz.com> writes:
>
> >
> > Hi,
> >
> > I'm plotting a multiple histogram using the function multhist {package
> > plotrix}, something like:
> >
> > library(plotrix)
> > mh <- list(rnorm(200, mean=200, sd=50), rnorm(200, mean=250, sd=50))
> > multhist(mh)
> >
> > In this graph y-axis represents the frequency of observations.... but I
> > would like it to be scaled into relative frequencies,
> >
> > does anybody know how to do this with multhist or similar function?
> >
> > thanks a lot,
> >
> > Ahimsa
> >
>
>    In its current form, multhist doesn't allow the
> freq=FALSE or prob=TRUE arguments to be passed to
> hist() (the ... argument passes optional arguments
> to barplot, not hist).  You could hack it as follows:
>
> pmulthist <-
> function (x, breaks = "Sturges", ...)
> {
>     allhist <- hist(unlist(x), breaks = breaks, plot = FALSE, freq=FALSE)
>     combhist <- t(sapply(x, function(z) hist(z, breaks = allhist$breaks,
>         plot = FALSE)$counts))
>     barplot(combhist, beside = TRUE, names = signif(allhist$mids,
>         2), ...)
> }
>
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
>



-- 
ahimsa campos-arceiz
www.camposarceiz.com

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