[R] trouble positioning legends on barplot written to a file

[Tom Arnold]

I'm trying to generate some plots for print publication and I'm having trouble
getting them the way I want. I get a plot with a legend that overlaps the bars
and looks bad. Also, I'm saving this as PDF file (whatever happened to the
"png" function to save as PNG format, in r 1.4.1?)

I've tried a number of things, which produce a number of questions.

1) it seems that the "legend" for a plot must be within the plot area. Is
there a way to put the legend above, below, or to the side of the plot? The
particular data I have fill up the plotting area (stacked bar charts, going to
100% in each bar)

2) I've tried using "locator()" to position the legend. This only works, so
far, if I am not using trying to divert output to another device -- like
creating a PDF via
pdf();
barplot(resultmat);
dev.off();

so if I take out the pdf() and the dev.off() and just do this:
barplot(resultmat);
legend(locator(1),legend=l,fill=colors);

it works, on the graphics display device window on screen.

However, if I do this:
pdf(onefile=FALSE);
barplot(resultmat);
legend(locator(1),legend=l,fill=colors);
dev.off();

I get:
>Error in legend(locator(1),legend = l : missing y

Also it doesn't let me specify a point. I suppose that's not so surprising,
because it is drawing to a non-interactive graphics device (the PDF "device"
is non-interactive, right?), but the error message is confusing.

So, is there any way to specify the location with locator() AND to save that
plot to a file?

And if I don't use "locator' then I have to specify the legend location to
"legend(x,y, legend) but the documentation doesn't say what coordinate system
that's supposed to be in.

TIA.

Tom Arnold

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