[R] Adding a line to a beside=TRUE barplot

[Galen Moore]

Many thanks, it works beautifully!  I'd not caught the use of colMeans() as
the path to useable x-coordinates, and was fixated on the existing
bargraph's x-vector for this purpose.

Ref your Q, I guess I had the lattice reference in there as a vestige of
other attempts to get the job done with barchart i/o barplot.

Galen

-----Original Message-----
From: Peter Ehlers [mailto:ehlers at ucalgary.ca] 
Sent: Friday, June 03, 2011 02:45
To: galen.a.moore at gmail.com
Cc: r-help at r-project.org
Subject: Re: [R] Adding a line to a beside=TRUE barplot

On 2011-06-02 13:09, Galen Moore wrote:
> Greetings –
>
>
>
> Grateful for any help on this one:
>
>
>
> In the following demo code, I am trying to get the points in the line 
> to appear over the same x-axis labels as are used by the paired Bars.  
> It appears, however, that R/lattice ignores the x-axis points used by 
> the bars and plots the x points for the line at ½ points.
>
>
>
> Can you help me tweak this code so that the nth bump in the line 
> appears over the same nth pair of bars?  I’m open to any options 
> besides lattice/barplot.
>
>
>
> library(lattice)
>
> aa<- abs(rnorm(c(1:10)))*5
>
> bb<- abs(rnorm(c(1:10)))*5
>
> cc<- abs(rnorm(c(1:10)))*5
>
>
>
> dd<- as.matrix(cbind(aa, bb))
>
>
>
> barplot(t(dd), beside=TRUE, ylim=c(0,10))
>
> lines(cc)

What's lattice doing here? barplot() is not a lattice function.

Careful reading of the help page for barplot and study of the examples will
lead you to:

   mp <- barplot(t(dd), beside=TRUE)
   mp
   lines(colMeans(mp), cc, col=2, lwd=3)


Peter Ehlers

>
>
>
> Many thanks,
>
>
>
> Galen
>
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