How can I load a field from a saved structure?

Question

K E 2016-5-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/282743-how-can-i-load-a-field-from-a-saved-structure

评论： Utku Arslan 2021-2-26

For my work, it is convenient to store measurement data in structures with many fields. The structure is useful for keeping all the measurements together, passing into functions that plot everything, etc. However the files get large and bulky to handle. I'd like to be able to load a specified field from the *.mat file containing the structure. I thought this was possible using this approach (saving with -struct flag), but only separate variables containing the fields are saved and the original structure is lost. Is there a way to retrieve a field out of an existing mat file containing a structure, as is shown below, perhaps using matfile ?

% Make the structure
a.Temperature.value = rand(1,10);
a.Temperature.units = 'C';
a.Humidity.value = rand(1,10);
a.Humidity.units = '%';
save('c:\temp\junk.mat', 'a'); % Save the structure
load('c:\temp\junk.mat', 'a.Temperature'); % Load a specified field (doesn't work)

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Answer 1

Adam 2016-5-5

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https://ww2.mathworks.cn/matlabcentral/answers/282743-how-can-i-load-a-field-from-a-saved-structure#answer_220923

编辑：Adam 2016-5-5

在 MATLAB Online 中打开

save('c:\temp\junk.mat', '-struct', 'a');
load('c:\temp\junk.mat', 'Temperature');

should work I think. Or

loadedVars =  load('c:\temp\junk.mat', 'Temperature');;
Temperature = loadedVars.Temperature;

if you prefer.

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K E 2016-5-6

I have put in a request to add the ability to load fields in future releases.

Utku Arslan 2021-2-26

在 MATLAB Online 中打开

I gotcha bro!

function importfile(fileToRead1)
%IMPORTFILE(FILETOREAD1)
%  Imports data from the specified file
%  FILETOREAD1:  file to read
% Import the file
newData1 = load('-mat', fileToRead1);
% Create new variables in the base workspace from those fields.
vars = fieldnames(newData1);
for i = 1:length(vars)
    assignin('base', vars{i}, newData1.(vars{i}));
end