Transfer a matrix in a quick way

a matrix' size is 4*300 i want to transfor it to 400*3

the method is

FROM

a a a b b b c c c ……（300 column）

a a a b b b c c c ……（300 column）

a a a b b b c c c ……（300 column ）

a a a b b b c c c ……（300column ）

TO

a a a

a a a

a a a

a a a

b b b

b b b

b b b

b b b

c c c

c c c

c c c

c c c

…… 400 ROW

it just changes some data's position . i need a quick way to do it , Thanks!!! --

[Andrei Bobrov]

a = kron(1:3,ones(4,3))

out = reshape(permute(reshape(a,size(a,1),3,[]),[1 3 2]),[],3)

Answer 1

[Geoff]

If you want to preserve each 4x3 block, you could try something like this:

B = reshape(A(:, [1:3:end, 2:3:end, 3:3:end]), [], 3 );

[yu xu]

thank you very much.

Answer 2

[Thomas]

You can use reshape

 doc reshape

Eg.

a={'a' 'a' 'a' 'b' 'b' 'b' 'c' 'c' 'c';'a' 'a' 'a' 'b' 'b' 'b' 'c' 'c' 'c';
'a' 'a' 'a' 'b' 'b' 'b' 'c' 'c' 'c';'a' 'a' 'a' 'b' 'b' 'b' 'c' 'c' 'c'}

out=reshape(a,3,[])'

 out=
    'a'    'a'    'a'
    'a'    'a'    'a'
    'a'    'a'    'a'
    'a'    'a'    'a'
    'b'    'b'    'b'
    'b'    'b'    'b'
    'b'    'b'    'b'
    'b'    'b'    'b'
    'c'    'c'    'c'
    'c'    'c'    'c'
    'c'    'c'    'c'
    'c'    'c'    'c'

[Geoff]

I have a feeling that those blocks of 'a', 'b' etc are supposed to maintain the same relative position in the output matrix. Reshape will scramble the order in this case. I think the poster wants to reorganise blocks of 4x3 data into a vertical stack.

[Thomas]

true, in this case im assuming a=a :)