如何使用 rgamma 对 r 中的 gamma 进行采样？

Question

If I want to sample Gamma(238, 10), why the code is

   theta <- rgamma(1000,238)/10

but not

  theta <- rgamma(1000,238, 10)

?

Answer 1

The third argument to rgamma is rate , an inverse multiplicative scale parameter, so actually these two ways are equivalent:

theta_1 <- rgamma(10000, 238, 10)
theta_2 <- rgamma(10000, 238) / 10

hist(theta_1)

hist(theta_2)