Question

I have a large real 1-d data set called r.
I would like plot:

 mean(log(1+a*r)) vs a, with a > -1 . 

How can i do this?

Answer 1

You can use sapply to evaluate the function on a set of values.

x <- seq(-1,1,length=20)
y <- sapply(x, function(a) mean(log(1+a*r)) )
plot(x,y, type="l")

Alternatively, you can define a function to compute this quantity
and use curve to plot it.
The function has to be vectorized.

r <- runif(100)
f <- function(a) mean(log(1+a*r))
f <- Vectorize(f)
curve(f, xlim=c(-1,1), las=1)