R help - May 2007 - Centering a legend

Using layout I am plotting 5 boxplots on top of each other,
all of them using colored boxes in different order.
In a 6th box below I want to give the legend explaining the box colors,
and I want this box to be centered in an otherwise empty plot.
I am creating this plot by
plot(0:1,0:1,type="n")

Is there an easy way to find the parameters x and y for calling legend
which will center the legend in this plot?



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Erich Neuwirth, University of Vienna
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On Mon, 2007-05-07 at 19:44 +0200, Erich Neuwirth wrote:
> Using layout I am plotting 5 boxplots on top of each other,
> all of them using colored boxes in different order.
> In a 6th box below I want to give the legend explaining the box colors,
> and I want this box to be centered in an otherwise empty plot.
> I am creating this plot by
> plot(0:1,0:1,type="n")
> 
> Is there an easy way to find the parameters x and y for calling legend
> which will center the legend in this plot?
Eric,

legend() has positional arguments to enable you to do what you require.

Something along the lines of the following:

# Do your plot
plot(0:1, 0:1, type = "n", ann = FALSE, axes = FALSE)

# Do the legend, centered
legend("center", "This is a test legend")


See the Details section of ?legend, third paragraph. Also, the last set
of examples there.

HTH,

Marc Schwartz