[R] Scatterplot - symbols coded by factor

[Prof Brian D Ripley]

On Fri, 9 Feb 2001, Matt Pocernich wrote:

> Hi - I would like to create a scatterplot with the symbols coded by a factor in each record.  Is their a better way than what I have used below?  I attempted to use the plot.factor, but cannot force it to make a scatterplot instead of boxplots.  I have considerd making a function with a 'for' statement for each level of the factor.  Is there a better way for when I am dealing with more levels of factors?
>
> Thanks,  Matt Pocernich
>
> Y <- c(40,38,30,47,25,32,13,35,27,24,20,13)
> X<-c(110,75,93,97,60,75,38,140,62,90,45,59)
> manuf <- factor(rep(LETTERS[1:3],c(4,4,4)))
> data3 <- data.frame(X,Y,manuf)
> attach(data3)
>
> plot(X, Y, type="n")
> points(X[manuf=="A"], Y[manuf=="A"], pch = "A")
> points(X[manuf=="B"], Y[manuf=="B"], pch = "B")
> points(X[manuf=="C"], Y[manuf=="B"], pch = "C")

You can use

> plot(X, Y, type="n")
> points(X, Y, pch=as.character(manuf))


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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