[R] Histogram questions
tov at ece.cmu.edu
Tue Feb 6 07:32:24 CET 2001
Thomas Lumley <tlumley at u.washington.edu> writes:
> On Mon, 5 Feb 2001, M. Edward (Ed) Borasky wrote:
> > 3. What would be even nicer is to have "hist" and "density" *both* scale their
> > outputs as probabilities, so they could be overlaid on a plot together. How
> > difficult is this to do?
> They both *do* scale their outputs as probability densities so they *can*
> be overlaid. They couldn't be overlaid if the bar heights added up to 1,
> since then the histogram wouldn't be a density estimate.
what appears to be working better for me in practice is to take care
> x <- rnorm(100)
> hh <- hist (x, prob=TRUE, plot=FALSE)
> dd <- density (x)
> hist (x, prob=TRUE, ylim=c(0, max(hh$intensities, dd$y)))
> lines (dd)
the reason I bring this up is that:
> hist (x, prob=TRUE)
is not the same as:
> plot (hh <- hist (x, prob=TRUE))
as one might naively expect...
mailto:tov at ece.cmu.edu (Tom Vogels) Tel: (412) 268-6638 FAX: -3204
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