Summing up values in a matrix

I have a 4D matrix, I(i,j,y,x) which has dimensions of 64 x 64 x 70 x 160. For each coordinate in y and x I'd like to sum all the values for I across i and j to form a 2D matrix I_y_x. i.e. I_y_x(0,0) = I(1,1,0,0)+I(1,2,0,0)+I(1,3,0,0) + .... + I(2,1,0,0) etc.

Thanks in advance

Answer 1

[Matt J]

sum(l,[1,2])

[Jonathan Bird]

Thanks for your response, I tried I_y_x = sum(I,[1,2]); but I_y_x is now also a 4D matrix instead of 2D.

[Matt J]

Just add a squeeze() or a reshape() operation

l=rand(64 , 64 , 70 , 160);

result=squeeze(sum(l,[1,2]));

whos result

  Name         Size             Bytes  Class     Attributes

  result      70x160            89600  double