How to reshapre a matrix?

Hi everyone,

I would like to reshape a matrix, say A:

rng default
A = randn(12,4)
A =

    0.5377   -1.3499    0.6715    0.8884
    1.8339    3.0349   -1.2075   -1.1471
   -2.2588    0.7254    0.7172   -1.0689
    0.8622   -0.0631    1.6302   -0.8095
    0.3188    0.7147    0.4889   -2.9443
   -1.3077   -0.2050    1.0347    1.4384
   -0.4336   -0.1241    0.7269    0.3252
    0.3426    1.4897   -0.3034   -0.7549
    3.5784    1.4090    0.2939    1.3703
    2.7694    1.4172   -0.7873   -1.7115
   -1.3499    0.7172   -2.9443   -0.1649
    3.0349    1.6302    1.4384    0.6277

into 3 bits that will be horizontally combined. So that the output would be a matrix B of dimensions 4x12, such as:

    B =

    0.5377    0.7254    0.4889    0.3252    0.3188   -0.1241    0.2939   -0.1022    3.5784    0.6715   -1.0689   -0.8649
    1.8339   -0.0631    1.0347   -0.7549   -1.3077    1.4897   -0.7873   -0.2414    2.7694   -1.2075   -0.8095   -0.0301
   -2.2588    0.7147    0.7269    1.3703   -0.4336    1.4090    0.8884    0.3192   -1.3499    0.7172   -2.9443   -0.1649
    0.8622   -0.2050   -0.3034   -1.7115    0.3426    1.4172   -1.1471    0.3129    3.0349    1.6302    1.4384    0.6277
   

The command reshape does not generate this output. I do not want to do something like B=[A(1:4,:) A(5:8,:) A(9:end,:)], since the matrix I am having is much larger than the example. Is there a generalized way to do it?

[Stephen23]

In matrix B, where do the values in the eighth and twelfth columns come from ? These do not exist anywhere in A: -0.1022, -0.2414, 0.3192, 0.3129, -0.8649, -0.0301.

[KALYAN ACHARJYA]

@Stephen Exactly.

[gsourop]

@Stephen My apologies, you are right. I changed the example and copied wrong values. Please let's consider the following matrices:

rng default
A = randn(12,4)

A =

    0.5377    0.7254    0.4889    0.3252
    1.8339   -0.0631    1.0347   -0.7549
   -2.2588    0.7147    0.7269    1.3703
    0.8622   -0.2050   -0.3034   -1.7115
    0.3188   -0.1241    0.2939   -0.1022
   -1.3077    1.4897   -0.7873   -0.2414
   -0.4336    1.4090    0.8884    0.3192
    0.3426    1.4172   -1.1471    0.3129
    3.5784    0.6715   -1.0689   -0.8649
    2.7694   -1.2075   -0.8095   -0.0301
   -1.3499    0.7172   -2.9443   -0.1649
    3.0349    1.6302    1.4384    0.6277


B =

    0.5377    0.7254    0.4889    0.3252    0.3188   -0.1241    0.2939   -0.1022    3.5784    0.6715   -1.0689   -0.8649
    1.8339   -0.0631    1.0347   -0.7549   -1.3077    1.4897   -0.7873   -0.2414    2.7694   -1.2075   -0.8095   -0.0301
   -2.2588    0.7147    0.7269    1.3703   -0.4336    1.4090    0.8884    0.3192   -1.3499    0.7172   -2.9443   -0.1649
    0.8622   -0.2050   -0.3034   -1.7115    0.3426    1.4172   -1.1471    0.3129    3.0349    1.6302    1.4384    0.6277

Answer 1

[Andrei Bobrov]

A =[...
       0.5377       0.7254       0.4889       0.3252
       1.8339      -0.0631       1.0347      -0.7549
      -2.2588       0.7147       0.7269       1.3703
       0.8622       -0.205      -0.3034      -1.7115
       0.3188      -0.1241       0.2939      -0.1022
      -1.3077       1.4897      -0.7873      -0.2414
      -0.4336        1.409       0.8884       0.3192
       0.3426       1.4172      -1.1471       0.3129
       3.5784       0.6715      -1.0689      -0.8649
       2.7694      -1.2075      -0.8095      -0.0301
      -1.3499       0.7172      -2.9443      -0.1649
       3.0349       1.6302       1.4384       0.6277];


[m,n] = size(A);
q = 4;

out = reshape(permute(reshape(A.',n,q,[]),[2,1,3]),q,[]);

[KALYAN ACHARJYA]

@Andrei sir you always rocks +1