Replace specific values in a matrix with zeros

Assume, I have two matrices like this:

A =
  35     1     6    26    19    24
   3    32     7    21    23    25
  31     9     2    22    27    20
   8    28    33    17    10    15
  30     5    34    12    14    16
B = [3 2 4 5 2 1];

I want to produce a matrix C below from matrix A & B like this:

C =
    35     1     6    26    19    24
     3    32     7    21    23     0
    31     0     2    22     0     0
     0     0    33    17     0     0
     0     0     0    12     0     0

where the ith element in matrix B determines "the number of elements in matrix A's ith column" that will bring to the ith column of the matrix C. For example, B(1) = 3 means that the 1st column of matrix C is equal to

[A(1:B(1),1) ; zeros(5-B(1),1)];

So is there any way for me to produce matrix C from A & B without using any "loop" command?

Answer 1

[Stephen23]

In one line:

>> A = [...
  35     1     6    26    19    24
   3    32     7    21    23    25
  31     9     2    22    27    20
   8    28    33    17    10    15
  30     5    34    12    14    16];
>> B = [3,2,4,5,2,1];
>> C = A.*bsxfun(@le,(1:size(A,1)).',B)
C =
          35           1           6          26          19          24
           3          32           7          21          23           0
          31           0           2          22           0           0
           0           0          33          17           0           0
           0           0           0          12           0           0

[Luan Nguyen Thanh]

Oh, wow, it works perfectly, thank you very much.

Answer 2

[Bshara Murr]

Hello, yes try this:

A =[35 1 6 26 19 24; 3 32 7 21 23 25; 31 9 2 22 27 20; 8 28 33 17 10 15; 30 5 34 12 14 16;];

B = [3 2 4 5 2 1];

[x y]= size(A);

C = zeros(x,y);

for i = 1:y

    for j = 1:B(i)

        C(j,i) = A(j,i);

    end

end

I just used the matrices you entered.

Answer 3

[KL]

Try this,

 [r c] = size(A);
 C = zeros(r,c);
 indx = bsxfun(@le,repmat((1:r).',1,c),repmat(B,r,1)) %find indicies
 C(indx) = A(indx)

 C =

   35    1    6   26   19   24
    3   32    7   21   23    0
   31    0    2   22    0    0
    0    0   33   17    0    0
    0    0    0   12    0    0