Convert multi dimensional array to a matrix

2017 2 17
1 个回答
更新时间：2018 8 7
4 次查看（30 天）

0 个投票

Let's say I have A = rand(2,2,2,2). Considering the last two index of the Array A(2,2,x,x) as positions in a matrix such that Matrix(1,1) = A(2,2,1,1) Matrix(1,2) = A(2,2,1,2)..... and so forth.
Ultimately I will end up with a 4,4 matrix in this case.
How can I do this without writing a loop. Please advise.
Update:
I think my question didn't come through correctly. I apologize for it.
Let's have
A(:,:,1,1) =
0.1455 0.8693
0.1361 0.5797
A(:,:,2,1) =
0.5499 0.8530
0.1450 0.6221
A(:,:,1,2) =
0.3510 0.4018
0.5132 0.0760
A(:,:,2,2) =
0.2399 0.1839
0.1233 0.2400
Now I want to have a new Matrix such that
1 2
1 M = [M11 M12;
2 M21 M22];
In my M11 I want A(:,:,1,1)
In my M12 I want A(:,:,1,2) and so forth.
Ultimately I have a 4X4 matrix.
Does it make sense?
Thank you

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回答（1 个）

Walter Roberson
Walter Roberson 2017-2-17

0 个投票

squeeze(A(2, 2, :, :))

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Arif Ahmed
Arif Ahmed 2017-2-18
Sorry. That doesn't work
James Tursa
James Tursa 2017-2-18
编辑：James Tursa 2017-2-18
Sure it does.
>> A = rand(2,2,2,2)
A(:,:,1,1) =
0.8147 0.1270
0.9058 0.9134
A(:,:,2,1) =
0.6324 0.2785
0.0975 0.5469
A(:,:,1,2) =
0.9575 0.1576
0.9649 0.9706
A(:,:,2,2) =
0.9572 0.8003
0.4854 0.1419
>> squeeze(A(2, 2, :, :))
ans =
0.9134 0.9706
0.5469 0.1419
>> [A(2,2,1,1) A(2,2,1,2); A(2,2,2,1) A(2,2,2,2)] % <-- the explicit elements
ans =
0.9134 0.9706
0.5469 0.1419
You get the same result with the squeeze method and by using the explicit element indexing you specified.
The question is why you think you would end up with a 4x4 matrix. What else about the result are you not telling us? Are you trying to rearrange all of the elements of A somehow? If so, then tell us how.
Arif Ahmed
Arif Ahmed 2017-2-18
编辑：Arif Ahmed 2017-2-18
I think my question didn't come through correctly. I apologize for it.
Let's have A(:,:,1,1) =
0.1455 0.8693
0.1361 0.5797
A(:,:,2,1) =
0.5499 0.8530
0.1450 0.6221
A(:,:,1,2) =
0.3510 0.4018
0.5132 0.0760
A(:,:,2,2) =
0.2399 0.1839
0.1233 0.2400
Now I want to have a new Matrix such that
1 2
1 M = [M11 M12;
2 M21 M22];
In my M11 I want A(:,:,1,1)
In my M12 I want A(:,:,1,2) and so forth.
Ultimately I have a 4X4 matrix.
Does it make sense?
James Tursa
James Tursa 2017-2-18
编辑：Stephen23 2017-2-18
Do you mean just this?
M = [A(:,:,1,1),A(:,:,1,2);
A(:,:,2,1),A(:,:,2,2)];
Your latest example doesn't seem to agree with the indexing for your original post.
Arif Ahmed
Arif Ahmed 2017-2-18
编辑：Arif Ahmed 2017-2-18
Yes. This is what I meant.
Yes, I agree it doesn't agree with my original post. I was thinking of including 2x2 matrix somehow it translated into (2,2,x,x) in writing. I apologize.
shaziah A
shaziah A 2018-8-7
Did you have chance to put them into a matrix? I am also trying to do the same and would really appreciate some help.

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