R help - Dec 2003 - barplot & plot together

Dear colleges,
I'm trying to combine a barplot and a plot in a single figure as follows:

data <- 1:6
t <- barplot(data, axes=F)
par(new= T)
plot(t, data, type="b")

However, as you can see in the example, the dots of the second plot do 
not fall in the midpoint of the bars in the first. Any trick for setting 
the 2 plots at the same scale?
I have unsuccessfully tried:
plot(t, data, type="b", xlim=c(0,7))
plot(t, data, type="b", xlim=c(min(t),max(t)))

(R 1.8.1, for Windows)

Thanks

Juli



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Juli G. Pausas
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Tel: (+ 34) 96 131 8227; Fax: (+ 34) 96 131 8190
mailto:juli at ceam.es
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"juli g. pausas" <juli at ceam.es> writes:
> Dear colleges,
> I'm trying to combine a barplot and a plot in a single figure as
follows:
> 
> data <- 1:6
> t <- barplot(data, axes=F)
> par(new= T)
> plot(t, data, type="b")
> 
> However, as you can see in the example, the dots of the second plot do
> not fall in the midpoint of the bars in the first. Any trick for
> setting the 2 plots at the same scale?
> I have unsuccessfully tried:
> plot(t, data, type="b", xlim=c(0,7))
> plot(t, data, type="b", xlim=c(min(t),max(t)))
> 
> (R 1.8.1, for Windows)
The canonical trick for getting two plots on the same scale is to set
xlim (and ylim) on *both*. On barplots, this gets a bit tricky since
you have to leave room for the column width (the actual calculation
can be read inside barplot.default). However, I'd try for something like

 t <- barplot(data,names=1:6,ylim=range(c(0,data*1.01)))
 points(t, data, type="b")


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907

>>>>> "juli" == juli g pausas <juli at ceam.es>
>>>>>     on Thu, 18 Dec 2003 10:54:08 +0100 writes:
    juli> Dear colleges,
    juli> I'm trying to combine a barplot and a plot in a single figure
as follows:

    juli> data <- 1:6
    juli> t <- barplot(data, axes=F)
    juli> par(new= T)
    juli> plot(t, data, type="b")

    juli> However, as you can see in the example, the dots of
    juli> the second plot do not fall in the midpoint of the
    juli> bars in the first. Any trick for setting the 2 plots
    juli> at the same scale?

yes, use

   bd <- barplot(data)
   points(bd, data, type = "b")

instead.  
A general recommendation: 
   Try to *not* use par(new = TRUE) if you can.

Martin