[R] Impaired boxplot functionality - mean instead of median
Marc Schwartz (via MN)
mschwartz at mn.rr.com
Thu Dec 1 22:30:58 CET 2005
On Thu, 2005-12-01 at 23:27 +0300, Evgeniy Kachalin wrote:
> Marc Schwartz (via MN) Ð¿Ð¸ÑÐµÑ:
> >>Marc Schwartz (via MN) Ð¿Ð¸ÑÐµÑ:
> >>So plotmeans is incapable of: boxplot(numerical~fact1+fact2). Is there
> >>any way further?
> > I think that somehow we are talking past each other here.
> > plotmeans() does what it is designed to do, which is to simplify the
> > process of plotting group-wise point estimates and user defined error
> > bars/intervals around the point estimates.
> > In your case, these intervals would be standard deviations around each
> > of the group means as you have indicated.
> > Review the examples in ?plotmeans.
> > As Martin and others have pointed out, you need to remove boxplots from
> > the equation here, as they were not designed to plot means and standard
> > deviations.
> Again, what I'm talking about: plotmeans is incapable of analyzing the
> formula. For example, I have two factors: A - a, b, c, and B - d, e, f.
> If i plot: boxplot(num~A+B) what do I get? Eight boxes: ad, ae, af, ba,
> be, bf, cd, ce, cf. If I plot: plotmeans(num~A+B) - what do I get?
> Nothing. Because plotmeans cannot combine two factors in various
> combination. Is there a simple way to do it?
> Anyway... That's wrong way, all what is neccessary is to have a boxplot
> with mean istead of median. Is there simple way to do it?
If we take SDs out of the picture for the moment, we can do something
# Do the boxplot as you want using the formula
boxplot(breaks ~ wool + tension, data = warpbreaks)
# Get the means using tapply() with an interaction of the
# factor levels for each group
means <- with(warpbreaks, tapply(breaks,
mean, na.rm = TRUE))
# Now add the means to the boxplot, where the
# x axis values are 1:number of groups by default
points(1:length(means), means, pch = 19)
> Statistical software like Statistica 7.0 offers any possible combination
> of what "Boxplot" could mean. Is it possible to have only one
> modification to R's boxplot?
> Thank you for kind answers.
> Also please tell me, where should I send replies: to conference adress
> or to those who answer me directly.
Generally best to "reply to all", which gets the message back to the
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others during searches.
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