Selecting rows based on criteria from previous row

Hello, I'm attempting to select specific rows of a matrix (size of which is (72,3) ) based on the criteria that the value of column 1 in the previous row = 0. So something

i = 1:72 X(i -1,1)==0? I've tried several different variations on this. I've also attempted naming rows with zero in the first column as something specific and selecting based on that, but can't seem to get it to work. Any help would be greatly appreciated it, thanks!

Sam DeWitt

Answer 1

[Andrei Bobrov]

c - your array [72 x 3]

x = c(:,1) == 0;
out = c([false;x(1:end-1)],:);

[sam dewitt]

Thank you so much!