Efficient way to reshape data

Question

David Velasco 2022-11-1

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1841048-efficient-way-to-reshape-data

编辑： Bruno Luong 2022-11-1

采纳的回答： David Hill

在 MATLAB Online 中打开

I am looking for an efficient way to reshape a matrix. Seems like a simple process, but I can't seem to get it right.

I have the following example. The real data will be much larger, but always an [n 3] matrix.

data = [ 1	2	3
         4	5	6
         7	8	9
         10	11	12
         13	14	15
         16	17	18
         19	20	21
         22	23	24];

And I'd like to end up with something like this:

>> data2
data2(:,:,1) =
     1     2     3
     4     5     6
data2(:,:,2) =
     7     8     9
    10    11    12
data2(:,:,3) =
    13    14    15
    16    17    18
data2(:,:,4) =
    19    20    21
    22    23    24

I'm sure using combinations of transpose, reshapre, repmat, and/or similar I can get to this with just one line of code, but I'm struggling to get there. I can use the following for loop and that does the job:

data2 = nan(2,3,4);
for i = 1:4
        data2(:,:,i) = data(i*2-1:2*i,1:3);
end

But I'm sure there's a more elegant and efficient way to do this. Any suggestions are appreciated.

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Answer 1

David Hill 2022-11-1

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1841048-efficient-way-to-reshape-data#answer_1088928

在 MATLAB Online 中打开

data = [ 1	2	3
         4	5	6
         7	8	9
         10	11	12
         13	14	15
         16	17	18
         19	20	21
         22	23	24];
permute(reshape(data',3,2,[]),[2 1 3])
ans = 
ans(:,:,1) =

     1     2     3
     4     5     6


ans(:,:,2) =

     7     8     9
    10    11    12


ans(:,:,3) =

    13    14    15
    16    17    18


ans(:,:,4) =

    19    20    21
    22    23    24