How to convert 4D double matrix into 2D arrays

Question

Sung Wook Choi 2023-11-13

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2046390-how-to-convert-4d-double-matrix-into-2d-arrays

评论： Dyuman Joshi 2023-11-15

采纳的回答： Dyuman Joshi

Hi

I'm sorry for my English :(

I'm trying to convert 4-D double matrix into 2D arrays

There are a total of 14 different scenarios, each represented by a matrix of size 1x101 in the program. The representation in 4D is structured as (:,:,1,1) through (:,:,101,1) for the first scenario, (:,:,1,2) through (:,:,101,2) for the second scenario, and so on, up to (:,:,1,14) through (:,:,101,14) for the fourteenth scenario. Each set of indices within the 4D structure corresponds to a unique value in the respective scenario.

Thank you so much

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Dyuman Joshi 2023-11-13

Yes, that's what I meant.

Ok, there are 2 singleton dimensions.

Now, What is the output you want? A 101x14 array?

Sung Wook Choi 2023-11-13

Yes I want it!

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Answer 1

Dyuman Joshi 2023-11-13

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2046390-how-to-convert-4d-double-matrix-into-2d-arrays#answer_1351415

在 MATLAB Online 中打开

Use squeeze -

in = rand(1,1,101,14);
size(in)
ans = 1×4
     1     1   101    14

out = squeeze(in);
size(out)
ans = 1×2
   101    14

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Dyuman Joshi 2023-11-13

在 MATLAB Online 中打开

scat.mat

I hope this is clear now -

load('scat.mat')
%Check the contents of the array
scat_amor_sweep
scat_amor_sweep = struct with fields:
    Lumerical_dataset: [1×1 struct]
                    f: [101×1 double]
               lambda: [101×1 double]
               radius: [3.5000e-08 4.0000e-08 4.5000e-08 5.0000e-08 5.5000e-08 6.0000e-08 6.5000e-08 7.0000e-08 7.5000e-08 8.0000e-08 8.5000e-08 9.0000e-08 9.5000e-08 1.0500e-07]
                sigma: [1×1×101×14 double]
%Assign the data to a variable
in = scat_amor_sweep.sigma;
size(in)
ans = 1×4
     1     1   101    14

%Remove the singleton dimensions from the variable
out1 = squeeze(in)
out1 = 101×14
0e-12 *

0057    0.0084    0.0119    0.0163    0.0217    0.0283    0.0352    0.0424    0.0495    0.0561    0.0627    0.0692    0.0753    0.0880
0057    0.0083    0.0117    0.0159    0.0212    0.0277    0.0347    0.0419    0.0491    0.0558    0.0625    0.0690    0.0753    0.0881
0057    0.0082    0.0116    0.0156    0.0208    0.0271    0.0341    0.0414    0.0487    0.0555    0.0622    0.0689    0.0751    0.0882
0057    0.0082    0.0115    0.0154    0.0204    0.0266    0.0336    0.0410    0.0483    0.0551    0.0620    0.0687    0.0750    0.0882
0057    0.0081    0.0113    0.0151    0.0199    0.0261    0.0330    0.0404    0.0479    0.0548    0.0617    0.0684    0.0749    0.0882
0057    0.0081    0.0112    0.0149    0.0195    0.0255    0.0324    0.0399    0.0474    0.0545    0.0614    0.0682    0.0747    0.0882
0058    0.0081    0.0111    0.0147    0.0192    0.0250    0.0319    0.0394    0.0470    0.0541    0.0611    0.0680    0.0745    0.0882
0059    0.0081    0.0110    0.0145    0.0188    0.0245    0.0313    0.0389    0.0465    0.0537    0.0608    0.0677    0.0743    0.0880
0060    0.0081    0.0110    0.0143    0.0185    0.0240    0.0307    0.0383    0.0461    0.0534    0.0605    0.0674    0.0740    0.0879
0061    0.0082    0.0109    0.0142    0.0182    0.0235    0.0300    0.0377    0.0456    0.0531    0.0602    0.0672    0.0738    0.0877

You can combine the above steps as well -

out2 = squeeze(scat_amor_sweep.sigma)
out2 = 101×14
0e-12 *

0057    0.0084    0.0119    0.0163    0.0217    0.0283    0.0352    0.0424    0.0495    0.0561    0.0627    0.0692    0.0753    0.0880
0057    0.0083    0.0117    0.0159    0.0212    0.0277    0.0347    0.0419    0.0491    0.0558    0.0625    0.0690    0.0753    0.0881
0057    0.0082    0.0116    0.0156    0.0208    0.0271    0.0341    0.0414    0.0487    0.0555    0.0622    0.0689    0.0751    0.0882
0057    0.0082    0.0115    0.0154    0.0204    0.0266    0.0336    0.0410    0.0483    0.0551    0.0620    0.0687    0.0750    0.0882
0057    0.0081    0.0113    0.0151    0.0199    0.0261    0.0330    0.0404    0.0479    0.0548    0.0617    0.0684    0.0749    0.0882
0057    0.0081    0.0112    0.0149    0.0195    0.0255    0.0324    0.0399    0.0474    0.0545    0.0614    0.0682    0.0747    0.0882
0058    0.0081    0.0111    0.0147    0.0192    0.0250    0.0319    0.0394    0.0470    0.0541    0.0611    0.0680    0.0745    0.0882
0059    0.0081    0.0110    0.0145    0.0188    0.0245    0.0313    0.0389    0.0465    0.0537    0.0608    0.0677    0.0743    0.0880
0060    0.0081    0.0110    0.0143    0.0185    0.0240    0.0307    0.0383    0.0461    0.0534    0.0605    0.0674    0.0740    0.0879
0061    0.0082    0.0109    0.0142    0.0182    0.0235    0.0300    0.0377    0.0456    0.0531    0.0602    0.0672    0.0738    0.0877

Sung Wook Choi 2023-11-15

Thank you so much! Finally, may I ask what the difference is between the 'out1' and 'out2' matrices? They appear to be the same, and I couldn't identify any distinctions.

Also, when you use 'squeeze,' it removes two singletons. Does 'squeeze' mean removing all singletons in a matrix?

Dyuman Joshi 2023-11-15

You are welcome!

Yes, they are the same.

For the second one, I have just combined all the steps in one command.

Yes, 'squeeze' removes all the singleton dimensions of an array.

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How to convert 4D double matrix into 2D arrays

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