[R] plotting group means

[Chuck Cleland]

On 9/9/2008 6:49 AM, Erich Studerus wrote:
> Hi all,
> 
>  
> 
> I want to plot the grouped means of some variables. The dependent variables
> and the grouping factor are stored in different columns. I want to draw a
> simple line-plot of means, in which the x-axis represents the variables and
> y-axis represents the means. The means of the groups should be connected by
> lines. So far, the only function that I could find comes closest to what I'm
> looking for, is the error.bars.by-function in the psych-package. To know,
> what I'm looking for, just type:
> 
>  
> 
> library(psych)
> x <- matrix(rnorm(500),ncol=20)
> y <- sample(4,25 ,replace=TRUE)
> x <- x+y
> error.bars.by(x,y,ci=0)
> 
>  
> 
> Now, I want to put a legend for the grouping factor of this graph. I also
> would like to manipulate the linetypes and colors of the lines. I've read
> the documentation, but it was not clear to me, how to do this. Are there
> other plotting functions in R, which can do the same?

  Here is an approach which uses xyplot() in the lattice package and
shows how to control line types and colors:

mydf <- data.frame(x=rep(paste("Group", 1:4, sep=""), 6),
                   v=rep(paste("Variable", 1:6, sep=""), each=4),
                   y=runif(24))

library(lattice)

xyplot(y ~ v, groups = x, data = mydf, type="b",
              xlab="Dependent Variables", ylab="Mean",
              auto.key=list(lines=TRUE, points=TRUE, space="right"),
              par.settings = list(superpose.symbol =
                                   list(pch=c(16,8,1,5),
                                        col=c("black","red","green","blue"),
                                        lty=c(1,2,3,4)),
                                  superpose.line =
                                   list(col=c("black","red","green","blue"),
                                        lty=c(1,2,3,4))))

> Erich
> 
>  
> 
> ________________________________________________
> 
> Erich Studerus
> Lic. Phil. Klinische Psychologie
> Psychiatric University Hospital Zurich
> Division of Clinical Research
> Lenggstr. 31
> CH-8008 Zurich
> Switzerland
> Mail: erich.studerus at bli.uzh.ch
> Office: +41 44 384 26 66
> Mobile: +41 76 563 31 54
> ________________________________________________
> 
>  
> 
> 
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-- 
Chuck Cleland, Ph.D.
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