extract the 16 elements (4 by 4 matrix) from a big matrix

Now i have a 4 by 16 matrix,we assume this matrix called A

1 2 1 2 5 6 5 6 9 10 9 10 13 14 13 14

3 4 3 4 7 8 7 8 11 12 11 12 15 16 15 16

1 2 1 2 5 6 5 6 9 10 9 10 13 14 13 14

3 4 3 4 7 8 7 8 11 12 11 12 15 16 15 16

i want to extract 4 matrix,16element for each ,that is

1 2 1 2 5 6 5 6 9 10 9 10 13 14 13 14

B= 3 4 3 4 C= 7 8 7 8 D= 11 12 11 12 E= 15 16 15 16

1 2 1 2 5 6 5 6 9 10 9 10 13 14 13 14

3 4 3 4 7 8 7 8 11 12 11 12 15 16 15 16

My thinking is when j=1,n=0,then f = A(1:4 , 1:4) ,so i can get the B matrix

when j=2,n=1,then f = A(1:4 , 5:8) ,so i can get the C matrix

when j=3,n=2,then f = A(1:4 , 9:12) ,so i can get the D matrix

when j=4,n=3,then f = A(1:4 , 13:16) ,so i can get the E matrix

Here is my code,i know this code is not right,but i don't know how to modify it.Can anyone teach me how to modify it to let the code result become what i want ?

for j=1:4
     for n=0:3
            f=A(1:4 , j+3*n : 4*j);
     end
end

[Stephen23]

You could use a cell array:

Z = mat2cell(A,4,[4,4,4,4]);

Although it is just as easy to access the data directly in the original matrix using basic indexing, without duplicating the data in memory. Splitting up data rarely makes processing data easier.

Answer 1

[KALYAN ACHARJYA]

Recommended: Comments by S. Cobeldick

As per your specific qiestion

My thinking is when j=1,n=0,then f = A(1:4 , 1:4) ,so i can get the B matrix

when j=2,n=1,then f = A(1:4 , 5:8) ,so i can get the C matrix

when j=3,n=2,then f = A(1:4 , 9:12) ,so i can get the D matrix

when j=4,n=3,then f = A(1:4 , 13:16) ,so i can get the E matrix

you can think about

A=randi(4,16);
n=0;
for j=1:4
   f{j}=A(1:4,j+3*n:4*j)
   n=n+1;
end

Now you call f{1},f{2}... cell arrays whenever it needed.

Answer 2

[Andrei Bobrov]

n = 4;
s = size(A,1);
out = reshape(A',s,n,[]);

Here:

out(:,:,1) -> B, out(:,:,2) -> C, out(:,:,3) -> D and etc.