MATLAB: Delete rows in matrix based on elements of the column vector

Question

Hi all,

I'm new to matlab and I need some help.

There is a matrix A = rand(10,4) and a column vector B = [0 0 1 1 2 2 3 3 4 4]'. I am trying to figure out how to clean A based on the values from B.

I would like to get rid of a row in A if there is 2 at the same position in B. In other words, if B(1) = 2 then A(1,:) = [ ]; and so on.

In my head it sounds like "if there is 2 in the column vector at the same position as this row in matrix then delete this row, do the same for the rest of rows". But this also will create a shift in matrix A, right? What function could perform this conditional cleaning on a huge matrix (5*10^6, 1000) based on corresponding column vector?

Thank you!

Answer 1

A(B==2,:) = []