[R] legend(): how to put variable in subscript?

[Aleksey Naumov]

Dear List,

I would like to plot a simple legend with two math expressions, e.g.

plot(0)
legend(1, 0.5, expression(sigma[i], sigma[j]))

The difficulty is that i and j should be variables rather than strings "i" and 
"j". In other words I'd like to do something like:

i = "A"
j = "B"
legend(1, 0.5, expression(sigma[i], sigma[j]))

and have "A" and "B" as the actual subscripts. I can substitute the variable 
in the expression e.g.:

legend(1, 0.5, substitute(sigma[i], list(i='A', j='B')))
legend(1, 0.5, bquote(sigma[.(i)]))

however, this gives me just one of the two entries in the legend. I cannot 
figure out how to include both sigmas in the legend.

What would be the best way to do something like this? Thank you for your ideas 
or suggestions.

Aleksey


-- 
Aleksey Naumov
Department of Geography
SUNY-Buffalo