What is Julia's equivalent of R's which?

The find function does that.

In R:

y = c(1,2,3,4)    
which(y > 2)     

In Julia:

y = [1, 2, 3, 4]    
find(y .> 2)    

There is no exact equivalent but findall

There is a comparison list of vocabularies for Julia vs R; which is on the list

http://www.johnmyleswhite.com/notebook/2012/04/09/comparing-julia-and-rs-vocabularies/

However, according to the list Julia's find is equivalent to R's which as answered by others.