modifying an identity matrix

I have an identity matrix. I want to put a '1' on the zeros that are right infront of the main diagonal, except at the very last '1'.

Is there an easy way to do it

Answer 1

[Walter Roberson]

I = eye(7)

I = 7×7

1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1

r = size(I,1);
newI = diag([ones(1,r-2), 0],-1) + I

newI = 7×7

1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 1