[R] Superposing data on boxplot

[Liaw, Andy]

Try:

y = rnorm(50)
z = factor(rep(1:5, each=10))
boxplot(y~z, horizontal=TRUE)
stripchart(y~z, add=TRUE)


HTH,
Andy

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> Ted.Harding at nessie.mcc.ac.uk
> Sent: Tuesday, May 04, 2004 10:48 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Superposing data on boxplot
> 
> 
> Hi folks,
> 
> I have a vaiable Y and an associated factor Z at several (13)
> levels.
> 
>   boxplot(Y~Z)
> 
> produces a nice array of boxplots, one for each level of Z,
> and each duly labaelled with its level of Z.
> 
> I would like to superpose on each boxplot the actual data
> points which it represents, i.e. do something conceptually
> (though not in real R) expressed as
> 
>   points(Y~Z)
> 
> or
> 
>   points(Z,Y)
> 
> It can be done "with bare hands" along the lines of
> 
>   B<-boxplot(Y~Z)
>   x<-bxp(B)
>   X<-rep(x,ngroups)
>   points(X,Y)
> 
> where ngroups is the number of data at each level of Z,
> *provided* the data are pre-sorted by level of Z and in the
> same order as these levels occurr in the boxplot. But of course
> they're not!
> 
> OK, I could do this by hand as well, but now it's getting a bit
> tedious, and I'm wondering if there's a better way.
> 
> Thanks for any suggestions,
> Ted.
> 
> 
> --------------------------------------------------------------------
> E-Mail: (Ted Harding) <Ted.Harding at nessie.mcc.ac.uk>
> Fax-to-email: +44 (0)870 167 1972
> Date: 04-May-04                                       Time: 15:48:23
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