MATLAB: Replace specific values in a matrix with zeros

matrix

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?

Best Answer

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
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