[R] question about mclust and prior probabilities

[Jocelyn Holden]

I'm sorry, this is probably a very simple question.  I am relatively 
new to R and am having difficulty understanding how to use the mclust 
options to change the prior probabilities for a mixture model.

I am dealing with a situation where I have 2 groups of data and it is 
known that the sample sizes are different in the population.  I want to 
incorporate the probability associated with each group into the mixture 
model to obtain better classification.

My current syntax is simply

mclust(data, G=2)

How can I modify this if I want to best represent a group split of 20 
in group 1 and 80 in group 2?