What is the best way to swap elements in an matrix ?

Hi,

I wonder what is the best way to swap elements in a matrix without having to use "for" loop.

For example: I have an array like this

A = [ a1b1 a1b2 a1b3 a2b1 a2b2 a2b3 a3b1 a3b2 a3b3;

c1d1 c1d2 c1d3 c2d1 c2d2 c2d3 c3d1 c3d2 c3d3]

and I want to swap the elements such that it results in the following array

B = [ a1b1 a2b1 a3b1 a1b2 a2b2 a3b2 a1b3 a2b3 a3b3 ;

c1d1 c2d1 c3d1 c1d2 c2d2 c3d2 c1d3 c2d3 c3d3 ]

Thanks

BL

[KSSV]

What are the elements of A and B? what is a1, b1 all these?

[BL]

Hi,

I tried to formulate it in a general way. So a1b1 is just a number. E.g.

A = [ a1b1 a1b2 a1b3 a2b1 a2b2 a2b3 a3b1 a3b2 a3b3] = [11 12 13 21 22 23 31 32 33].

Just tried to show what is the desired swapping that I want to have.

Answer 1

[Walter Roberson]

A = [
    1121 1122 1123 1221 1222 1223 1321 1322 1323
    3141 3142 3143 3241 3242 3243 3341 3342 3343
    ]

A = 2×9

1121 1122 1123 1221 1222 1223 1321 1322 1323 3141 3142 3143 3241 3242 3243 3341 3342 3343

B = [
    1121 1221 1321 1122 1222 1322 1123 1223 1323
    3141 3241 3341 3142 3242 3342 3143 3243 3343
    ]

B = 2×9

1121 1221 1321 1122 1222 1322 1123 1223 1323 3141 3241 3341 3142 3242 3342 3143 3243 3343

B2 = reshape(permute(reshape(A, 2, 3, 3),[1 3 2]), 2, [])

B2 = 2×9

1121 1221 1321 1122 1222 1322 1123 1223 1323 3141 3241 3341 3142 3242 3342 3143 3243 3343

B - B2

ans = 2×9

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0