how to interchange the elements of a vector/matrix?

hi

a,b,c,d all are 2x1 matrices.

i will run a for loop and with each loop the elements of matrix x will increase.

example-

for i=1, x=[a1]

for i=2, x=[a1 b1 b2]

for i=3, x=[a1 b1 b2 c1 c2 c3 c4]

for i=3 x=[a1 b1 b2 c1 c2 c3 c4 d1 d2 d3 d4 d5 d6 d7 d8]

now after i=2, i want to rearrange the matrix to look like

y=[b1 a1 b2].

after i=3, i want to rearrange the matrix to look like

y=[c1 b1 c2 a1 c3 b2 c4]

after i=4, i want to rearrange the matrix to look like

y= [d1 c1 d2 b1 d3 c2 d4 a1 d5 c3 d6 b2 d7 c4 d8].

please tell me how i can do this?

basically all the new elements will be placed in between the existing elements.

[lokender Rawat]

It is quite easy to do that. But you have not specified how the data in a,b,c and d are present. Because to get the desired output in each iteration, the number of elements in:

'a' should be 1,

'b' should be 2,

'c' should be 4,

'd' should be 8.

Please specify the format of input data. How a,b,c and d are fed as input to the program? Are they all present in a matrix? Or individual vectors?

[Muhammad Ridwanur Rahim]

hi,

i will run a function and the function will output

for i=1 a 2x1 matrix

for i=2, a 2x2 matrix

for i=3, a 2x3 matrix

for i=4, a 2x4 matrix.

and then i would like to rearrange the columns of the matrices as mentioned in the original post.

a,b,c,d are all basically the outputs of the function.

for better understanding, i have denoted them different name so that i could explain how i want them to be rearranged.

[Muhammad Ridwanur Rahim]

basically i run run a function in a loop.

for i=1, function_output=[a11; a21], rearrange_output=[a11; a21]

for i=2, function_output=[b11 b12;b21 b22], rearrange_output=[b11 a11 b12; b21 a21 b22]

for i=3, function_output=[c11 c12 c13 c14;c21 c22 c23 c24], rearrange_output=[c11 b11 c12 a11 c13 b12 c14; c21 b21 c22 a21 c23 b22 c24]

and so on and so forth.

Answer 1

[Stephen23]

This works:

for k = 1:4
    % fake data:
    new = zeros(2,pow2(k-1));
    new(:) = 10*k+(1:numel(new));
    % zip data together:
    if k==1
        out = new
    else
        out = [reshape([new(:,1:end-1);out],2,[]),new(:,end)]
    end
end

It displays this in the command window:

out =
   11
   12
out =
   21   11   23
   22   12   24
out =
   31   21   33   11   35   23   37
   32   22   34   12   36   24   38
out =
   41   31   43   21   45   33   47   11   49   35   51   23   53   37   55
   42   32   44   22   46   34   48   12   50   36   52   24   54   38   56

[lokender Rawat]

I agree with @Stephen, this will work in your case @Muhammad Ridwanur Rahim