How to reassign values to new array without using a loop

I am trying to reassign values to a new matrix as a method of cleaning up / bookeeping / decreasing memory. My current code is as follows.

for i = 1:N,
    newMat(i,:) = oldMat(dataVec1 == dataVec2(i), :);
end

This loop takes FOREVER to do as N is very large and length(dataVec1) > N. Is there a way to avoid a for loop to achieve this? I have tried using bsxfun, but the intermediate matrix far exceeds memory.

Answer 1

[David Hill]

[~,idx]=ismember(dataVec2,dataVec1);
newMat=oldMat(idx,:);

[Master Yoda]

Holy cow! Such an elegant solution. Thanks so much!