Does an expected value command exist in R

问题

I'm sure there must be a straight forward command for this, but I've searched and can't find one. How do I get the expected value from a vector?

Here are the values

y <- c(0.05, 0.01, -0.1)

And their probabilities

p <- c(0.2, 0.7, 0.1)

I can get E(Y) by doing

sum(y*p)

But I think there is probably a command for it right, I just can't find it. Thanks!

回答1:

You can use weighted.mean:

weighted.mean(y, p)
# [1] 0.007

回答2:

Here's another option:

> c(y %*% p)
[1] 0.007

来源：https://stackoverflow.com/questions/26959127/does-an-expected-value-command-exist-in-r