[R] Matching vector order by indicators in a matrix

[Jeremy Beaulieu]

Hi all~

I have a bit of stupid question. And I promise, I have struggled through this and it sort of pains me to post this question... 

I have the following vector which is are the estimated parameter values output from "optim". 

$Rates
[1] 0.006280048 0.330934659

I want to match the order in the vector by the number in the following matrix:

$Index.matrix

ALPHA    1 1
BETA       2 2

In other words, the first value in $Rates should go wherever there is a "1" in the $Index.matrix. And the second value should go wherever there is a "2", and so on. I have some pretty hacky solutions, but I wanted to see if there was an easy way to do this that I am completely missing.

Thanks and all the best,

Jeremy