Placing values in a matrix with values from another matrix

Hello, I have some issues merging two different matrices.

I have one matrix, A (4915x90), and another matrix B (26x90). Matrix A contains only 0's and 1's and each column has 26 1's grouped together (i.e. two columns will never have 1's placed on the same row). I want to change all values given as 1's in each column in the A-matrix, with the values in each column in B. The values in each column in B (26 in total) are to be inserted in the same column in A, however, starting on a different rows depending on where the 26 1's are placed.

E.g., a shorter example.

A =
    0    0    0
    0    0    0
    1    0    0
    1    0    0
    1    0    0
    1    0    0
    0    0    0
    0    1    0
    0    1    0
    0    1    0
    0    1    0
  
     
B = 
    1    4    0 % I want to insert the four values in column 1 in B into column 1 in A,
    3    7    0 % and the values in column 2 in B into column 2 in A where the 1's are currently located
    5    8    0
    6    9    0   

Any help on where to begin would be greatly appreciated as my Matlab-skills aren't too advanced.

Answer 1

[Matt J]

A(A==1)=B;