Index Matrix A and Matrix B Problems

i have matrix A and Matrix B

A = [[ 0, 1, 1, 0, 1, 0,1],

[ 0, 0, 1, 1, 0, 0,0],

[ 1, 1, 0, 1, 1, 0,0]],

B = [[ 234, 59, 15, 99, 61, 74 ,71],

[ 16, 27, 14, 13, 111, 345.67],

[ 54, 23, 16, 14, 13, 27,100]],

How to make the value in matrix B be 0 if the value in matrix A is 1.

For example, in matrix A (row 1, column 2), the value of 1 in matrix B (row 1, column 2) will be 0.

I tried using loop but it didn't work. Thank you

Answer 1

[James Tursa]

You can use logical indexing:

B(A==1) = 0;

You can use a loop for this also, but you would have to show us the code you used before we can tell you what you did wrong with that approach.

[jane]

thank you

[James Tursa]

If on the other hand you want the A==1 spots to contain original B values and the other spots to become zero, then simply change the comparison operator used from "equals" to "not equals":

B(A~=1) = 0;

[jane]

Thanks James

Answer 2

[Voss]

A = [ 0, 1, 1, 0, 1, 0,1;  0, 0, 1, 1, 0, 0,0; 1, 1, 0, 1, 1, 0,0]

A = 3×7

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

B = [ 234, 59, 15, 99, 61, 74 ,71;  16, 27, 14, 13, 111, 345,67; 54, 23, 16, 14, 13, 27,100]

B = 3×7

234 59 15 99 61 74 71 16 27 14 13 111 345 67 54 23 16 14 13 27 100

B(A == 1) = 0

B = 3×7

234 0 0 99 0 74 0 16 27 0 0 111 345 67 0 0 16 0 0 27 100

[jane]

What if the matrix A has a value of 1, then the value in matrix B will contain the value of Matrix B itself and the other rows of columns contain the number 0.

for example, in matrix A (row 1, column 2), the value of 1 in matrix B (row 1, column 2) will contain the value of matrix b and the other column rows are worth 0.

[Voss]

A = [ 0, 1, 1, 0, 1, 0,1;  0, 0, 1, 1, 0, 0,0; 1, 1, 0, 1, 1, 0,0]

A = 3×7

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

B = [ 234, 59, 15, 99, 61, 74 ,71;  16, 27, 14, 13, 111, 345,67; 54, 23, 16, 14, 13, 27,100]

B = 3×7

234 59 15 99 61 74 71 16 27 14 13 111 345 67 54 23 16 14 13 27 100

B(A ~= 1) = 0

B = 3×7

0 59 15 0 61 0 71 0 0 14 13 0 0 0 54 23 0 14 13 0 0

[jane]

Thank You

[Voss]

You're welcome!

Answer 3

[Dhritishman]

MATLAB provides logical indexing which can be used to select or modify elements of a matrix.

A = [0, 1, 1, 0, 1, 0, 1; 0, 0, 1, 1, 0, 0,0; 1, 1, 0, 1, 1, 0,0]

A = 3×7

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

B = [234, 59, 15, 99, 61, 74, 71; 16, 27, 14, 13, 111, 345, 67; 54, 23, 16, 14, 13, 27, 100]   

B = 3×7

234 59 15 99 61 74 71 16 27 14 13 111 345 67 54 23 16 14 13 27 100

% This line of code changes the value in matrix B to 0 if the value of the corresponding element in matrix A is 1.
B(A == 1) = 0

B = 3×7

234 0 0 99 0 74 0 16 27 0 0 111 345 67 0 0 16 0 0 27 100