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Editorial Team
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Asked: 2026-05-23T15:04:03+00:00

I am trying to import data from a saved MATLAB struct array, but it

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I am trying to import data from a saved MATLAB struct array, but it seems that Mathematica is only importing the first element.

MATLAB

blank = struct('x', [], 'y', [], 'z', []);
data = repmat(blank, 1, 10);

for i = 1:10
    data(i) = struct('x', i, 'y', i * 2, 'z', i * 3);
end

save('test.mat', 'data');

Mathematica

In[76]:= Import["test.mat", "LabeledData"]
Out[76]= {"data" -> {"x" -> {{1.}}, "y" -> {{2.}}, "z" -> {{3.}}}}

Does anyone know why this is happening?

As a temporary fix, I’ve simply resorted to storing multiple struct’s in a cell array, i.e.

data{i} = struct(...)

Mathematica seems to be able to handle that fine.

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1 Answer

  1. Editorial Team

    I can’t really explain the behavior but in order to be able to read the files in Mathematica it is better to specify the Matlab version you are using. In MATLAB try the saving data with version 6.

    >> save('test.mat', '-v6', 'data')

    Then in mathematica:

    In[1]:= Import["test.mat", "LabeledData"]
Out[1]= {"data" -> {"x" -> {{1.}}, "y" -> {{2.}}, "z" -> {{3.}}}, {{2.}}, {{4.}}, {{6.}}, {{3.}}, {{6.}}, {{9.}}, {{4.}}, {{8.}}, {{12.}}, {{5.}}, {{10.}}, {{15.}}, {{6.}}, {{12.}}, {{18.}}, {{7.}}, {{14.}}, {{21.}}, {{8.}}, {{16.}}, {{24.}}, {{9.}},{{18.}}, {{27.}}, {{10.}}, {{20.}}, {{30.}}}

    I tried saving with v4 but that doesn’t work in MATLAB. Notice that the documentation in Mathematica says that “Import fully supports Versions 4 and 5 of the MAT format.”. I Hope this helps.

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