[R] relative frequency plot

Philipp Pagel philipp.pagel.lists at t-online.de
Thu Apr 27 20:32:34 CEST 2006

On Thu, Apr 27, 2006 at 10:48:39AM -0700, nlei at sfu.ca wrote:
> Hi All,
> I want to use "hist" to get the relative frequency plot. But the range of
> ylab is greater than 1,which I think it should be less than 1 since it
> stands for the probability.
> I'm confused. Could you please help me with it?

I was pretty confused by that, too at first. The solution is that
freq=False cause hist to plot the DENSITY rather than frequency. And
density is not necesssarily the same as relative frequency. Excerpt from

 density: values f^(x[i]), as estimated density values. If
          'all(diff(breaks) == 1)', they are the relative frequencies
          'counts/n' and in general satisfy sum[i; f^(x[i])
          (b[i+1]-b[i])] = 1, where b[i] = 'breaks[i]'.

If you want relative distance try something like this:

myhist = hist(x,breaks=52, plot=F)
myhist$counts = myhist$counts / sum(myhist$counts)

Not exactly clean, though -- we are messing with the myhist object...


Dr. Philipp Pagel                            Tel.  +49-8161-71 2131
Dept. of Genome Oriented Bioinformatics      Fax.  +49-8161-71 2186
Technical University of Munich
Science Center Weihenstephan
85350 Freising, Germany


Institute for Bioinformatics / MIPS          Tel.  +49-89-3187 3675
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