Create pyramid checkerboard matrix MATLAB

Question

I'd like to create a pyramid shaped checkerboard on a white background. It needs to be a large matrix (1186,686) or I would just do it manually. A simplified version of what I'm after is below:

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

Answer 1

Here's an attempt, it is half-vectorized since I could not figure out how to do this without a for-loop yet.

function B = board(rows, cols, centerright)
    c2 = cols/2;
    mid = floor(c2);
    if c2 ~= int32(c2) || centerright
        mid = mid + 1;
    end

    B = zeros(rows,cols);
    for row = 2:min([rows, mid+1, cols-mid+2])
        offset = row-2;
        newr = zeros(1, cols);
        newr([mid-offset:2:mid+offset]) = 1;
        B(row,:) = newr;
    end
end

Demo:

>> board(6,9)
ans =
     0     0     0     0     0     0     0     0     0
     0     0     0     0     1     0     0     0     0
     0     0     0     1     0     1     0     0     0
     0     0     1     0     1     0     1     0     0
     0     1     0     1     0     1     0     1     0
     1     0     1     0     1     0     1     0     1
>> board(6,10,0)
ans =
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     1     0     0     0     0     0
     0     0     0     1     0     1     0     0     0     0
     0     0     1     0     1     0     1     0     0     0
     0     1     0     1     0     1     0     1     0     0
     1     0     1     0     1     0     1     0     1     0
>> board(6,10,1)
ans =
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     1     0     0     0     0
     0     0     0     0     1     0     1     0     0     0
     0     0     0     1     0     1     0     1     0     0
     0     0     1     0     1     0     1     0     1     0
     0     1     0     1     0     1     0     1     0     1