replacing a matrix in loop

hi. i want to replace the matrix a in x(1,i) , when the x(1,i) == 0 and matrix b, when the x(1,i) == 1.

how could i do this?

clc; clear all; close all;
a = [ 1 1 1 0 0 0 ]
b = [ 0 0 0 1 1 1 ]

% Creating Random 0,1 in 10 times:
x = [ 1 1 0 0 ] % x has 4 column

for i=1:1:4
    if x(1,i) == 0
        x(1,i) = a;
    elseif x(1,i) == 1
         x(1,i) = b;
    end
end

my code is wrong. how could i do this work? i know for example x(1,1) = 1 , how could i replace matrix with x(1,1)?

[Jan]

I do not understand, what you want to achieve.

Answer 1

[Akshit Bagde]

Hi!

You won't be able to perform x(1,i) = a because the size of the left side is 1-by-1 and the size of the right side is 1-by-6.

You can try this!

a = [ 1 1 1 0 0 0 ];
b = [ 0 0 0 1 1 1 ];
x = [ 1 1 0 0 ];


% x has 4 Columns, a & b has 6 columns
for i=1:6:24
    if x(i) == 0
        x = [x(1:i-1) a x(i+1:end)]; % Replace x(i) with a
    elseif x(i) == 1
        x = [x(1:i-1) b x(i+1:end)]; % Replace x(i) with b
    end
end

Answer 2

[Stephen23]

Do NOT use a loop for this! Do NOT expand any arrays inside loops!

A simpler and much more efficient approach using a comma-separated list:

a = [1,1,1,0,0,0];
b = [0,0,0,1,1,1];
x = [1,1,0,0];
c = {a,b};
z = [c{1+x}]

z = 1×24

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

All MATLAB beginners need to learn how to use comma-separated lists effectively:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

so that they can learn how to write simple and efficient MATLAB code.