Find the indices of last occurrence of the unique elements in a vector

Question

I have an unordered vector v like the one shown below and would like to find the indices of the last occurrence of every unique elements in the list.

v <- scan(text="1 2 1 2 1 1 1 3 1 2 2 3 3 3 1 1 1 4 1 1 1 4 1 5 5 6
                6 2 3 3 4 4 2 2 2 2 2 3 3 3 1 4 4 4 3 2 5 5 5 5")
v
# [1] 1 2 1 2 1 1 1 3 1 2 2 3 3 3 1 1 1 4 1 1 1 4 1 5 5 6 6 2 3 3 4 4 2 2 2 2 2 3 3 3 
# [41] 1 4 4 4 3 2 5 5 5 5

Expected result (in order of 1, 2, 3, 4, 5):

41 46 45 44 50

I know I can use unique(unlist(v)) to find the unique elements but then how to find the indices of their last appearance? Any idea?

Thanks in advance.

Answer 1

Another approach that works even if the data are not ordered:

length(v1)-match(unique(v1),rev(v1))+1