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breaks in hist()

4 messages · Maarten van Gelder, Brian Ripley, Peter Dalgaard +1 more

#
Sorry, I forgot to mention in my earlier post that I run version 1.2.3 on
NT4.0

I was using the hist() function to create a frequency table of some network
traffic data. The range in values is rather large, from 0 till just under
10e12. Calling hist(x, breaks=c(0,1000,1e6,1e9,1e12),plot=F,freq=T) causes
hist() to return :

$breaks
[1] -1.0000e+05  1.0100e+05  1.1000e+06  1.0001e+09  1.0000e+12

Is this recalculation of the breaks by hist() intended?

Maarten van Gelder.
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#
On Tue, 26 Jun 2001, Maarten van Gelder wrote:

            
Thanks: hist has been changed several times recently.
Yes.  You have got caught by the following:

    fuzz <- if (right)
        c(if (include.lowest) -diddle else diddle, rep(diddle, length(breaks) - 1))
    else c(rep(-diddle, length(breaks) - 1), if (include.lowest) diddle else -diddle)
    breaks <- breaks + fuzz

Don't you want to use log10 scale?
#
Prof Brian Ripley <ripley at stats.ox.ac.uk> writes:
or just table(cut(x,breaks=c(0,1000,1e6,1e9,1e12)))

Basically, just don't expect hist() to do sensible things with things
that cannot sensibly be plotted. (Your first column would have a width
of one billionth of the total scale, whereas the last one takes up
99.9% of the total!)
#
It turns out I have one of the books here. It's _A Practical Guide To Heavy
Tails_ (Adler, Feldman, Taqqu editors, Birkhauser is the publisher) and there
are a few chapters on analysis of network traffic. My own applications are far
less sophisticated than this book; we don't have that kind of data.
--
znmeb at aracnet.com (M. Edward Borasky) http://www.aracnet.com/~znmeb

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