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Concatenate I x J*2 x K matrix in I*J x 2 x K matrix

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Janio Piguave
Janio Piguave 2019 年 12 月 3 日
Commented: Janio Piguave 2019 年 12 月 3 日
Hi Guys,
I was using this code line for concatenate a [8 x 4 x 6] matrix in a [16 x 2 x 6] matrix:
X = [x(:,1:2,:); x(:,3:4,:)];
M1 (2).png
Now, I am trying to convert a [200 x 200 x 11] matrix in a [40000 x 2 x 11] matrix, using the code line before mentioned:
X = [x(:,1:2,:); x(:,3:4,:); x(:,5:6,:); x(:,7:8,:); x(:,9:10,:); x(:,11:12,:); x(:,13:14,:); x(:,15:16,:); x(:,17:18,:); x(:,19:20,:); ...
(and so on)
x(:,181:182,:); x(:,183:184,:); x(:,185:186,:); x(:,187:188,:); x(:,189:190,:); x(:,191:192,:); x(:,193:194,:); x(:,195:196,:); x(:,197:198,:); x(:,199:200,:)];
It works, but I can do the same with a for loop (or another approach), and for general matrix array?
[I x J*2 x K] to [I*J x 2 x K]
Thanks for your help in advance.

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採用された回答

Stephen Cobeldick
Stephen Cobeldick 2019 年 12 月 3 日
編集済み: Stephen Cobeldick 2019 年 12 月 3 日
Use reshape and permute, e.g. for two columns:
>> A = randi(9,8,4,6); % fake data
>> A(:,:,1)
ans =
9 1 4 6
7 9 7 7
5 6 3 4
6 5 3 5
2 5 3 6
7 2 5 9
1 5 5 2
5 6 4 1
>> B0 = [A(:,1:2,:);A(:,3:4,:)]; % your method for comparison
>> [R,~,P] = size(A);
>> B1 = reshape(permute(reshape(A,R,2,[],P),[1,3,2,4]),[],2,P);
And checking:
>> isequal(B0,B1)
ans = 1
>> B0(:,:,1)
ans =
9 1
7 9
5 6
6 5
2 5
7 2
1 5
5 6
4 6
7 7
3 4
3 5
3 6
5 9
5 2
4 1
>> B1(:,:,1)
ans =
9 1
7 9
5 6
6 5
2 5
7 2
1 5
5 6
4 6
7 7
3 4
3 5
3 6
5 9
5 2
4 1
An example with six columns:
>> A = randi(9,3,6,5); % fake data
>> A(:,:,1)
ans =
2 3 8 8 2 6
5 5 1 5 6 7
2 2 1 8 1 1
>> B0 = [A(:,1:2,:);A(:,3:4,:);A(:,5:6,:)]; % your method for comparison
>> [R,~,P] = size(A);
>> B1 = reshape(permute(reshape(A,R,2,[],P),[1,3,2,4]),[],2,P);
And checking:
>> isequal(B0,B1)
ans = 1
>> B0(:,:,1)
ans =
2 3
5 5
2 2
8 8
1 5
1 8
2 6
6 7
1 1
>> B1(:,:,1)
ans =
2 3
5 5
2 2
8 8
1 5
1 8
2 6
6 7
1 1

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Janio Piguave
Janio Piguave 2019 年 12 月 3 日
Thanks for you help!. The cole provide me the matrix required.

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