I was wondering how to go about doing a matrix-vector multiplication using
hadoop. I have my matrix in one file and my vector in another. All the map
tasks will need the vector file... basically they need to share it.
Basically I want my map function to output key-value pairs (i,m[i,j]*v(j)),
where i is the row number, and j the column number; v(j) is the jth element
in v. And the reduce function will sum up all the values with the same key -
i, and that will be the ith element of my result vector.
I don't know how to format the input to do this.. even if I do it in 2 MR
iterations, first formatting the input and second the actual
matrix-vector-multiply, I don't have a clear idea.
If you have any ideas/suggestions I would appreciate it!
Thanks in advance,