[R] legend with math (greek letters) symbols
Julio Sergio Santana
juliosergio at gmail.com
Sun Sep 14 02:55:00 CEST 2014
I need to add a legend with three entries that should
contain a greek letter (lambda). I learnt that it is
possible using the function expression. So I need to
build the expressions from the lambdas vector, and I
simply cannot do it. This is the uggly result I got:
x <- 0:20
cc <- c("yellow", "springgreen", "navyblue")
lambdas <- c(6, 10, 13)
ds <- as.data.frame(lapply(lambdas, function(ll) dpois(x, ll)))
names(ds) <- lambdas
funcs <- list(plot, lines)
for (i in 1:3) {
ff <- funcs[[1+(i!=1)]]
ff(x,ds[[i]], type="o", pch=21,bg=cc[i])
}
# I can't build the expressions:
q <- list(expression(lambda==6), expression(lambda==10),
expression(lambda==13))
legend("topright",
legend=q,
lty=1, pch=21, pt.bg=cc)
legend() doesn't interpret the expressions and then it doesn't show
the lambda symbol.
Do you have any comments on this?
Thanks,
-Sergio.
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