How can I export fields from a series of .mat struct files into seperate .csv files in a loop while maintaining the field names as the new file names?

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Vítor
Vítor 2023-4-11
编辑： Arjun 2024-9-30
I have a bunch of struct files inside a folder. The only files present in the folder are the .mat struct files. Each .mat file is a 1x1 struct with 8 fields, and each field is a M x 5 double (M is constant inside the same struct, varying only between struct files). Both the .mat files and the fields are named according to a code for future reference (for simplicity and confidentiality, lets say the .mat files are named like APA1470fG; APA2470fG; APA3480fG (...) and the fields are named like APA4701hJ; APA4702hJ; APA480kJ (...). I need to export each field as a separate .csv file for analysis, but I wanted to create a loop so that I wouldn't have to export each and every single one manually, as there are simply too many fields in total that need to be exported, but I also need to be careful about the file names. Just to note that the actual names for both the struct and fields are very complex, so I don't see a way to load or save files using a logical naming approach in order to keep the existing names.
So, what I wanted to make was a loop that goes as follows:
  • Load each struct from the main folder at a time;
  • Create a folder inside the main folder with the same name as the .mat struct file;
  • Save each field as a .csv file with the same name as the field and save it on the created folder.
I would deeply appreciate if anyone could help me with my problem.

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回答（1 个）

Arjun
Arjun 2024-9-30
编辑：Arjun 2024-9-30
Hi @Vítor,
As per my understanding, you want to perform file manipulation involving .mat file. Specifically, you want to read .mat files that contain a 1x1 struct and then export each field of this struct as a separate .csv file. Each .csv file should be placed inside a dedicated folder corresponding to the .mat file from which it originated.
We can follow the following steps for automating this process:
  • Set the path to the folder containing .mat files
  • Use the “dir” function to list all the .mat files in the folder
  • Load the data from each .mat file
  • Use the “fieldnames” function to obtain the name of the struct’s fields
  • Create new folder named after each .mat file
  • Loop through each field in the struct and save it as a .csv file using “writematrix” function.
You can refer to the following code for better understanding:
% Address of the folder contain gthe .mat file
mainFolder = 'path_to_your_folder containing .mat files';
% Get a list of all .mat files in the folder
matFiles = dir(fullfile(mainFolder, '*.mat'));
% Scan each .mat file, extract the struct and fields
for k = 1:length(matFiles)
% Load the kth .mat file after fetching the name
matFileName = matFiles(k).name;
matFilePath = fullfile(mainFolder, matFileName);
dataStruct = load(matFilePath);
% Extract the name of the fields of the struct
structFieldNames = fieldnames(dataStruct);
mainStruct = dataStruct.(structFieldNames{1});
% Create a new folder with the same name as the .mat file
[~, folderName, ~] = fileparts(matFileName);
newFolderPath = fullfile(mainFolder, folderName);
if ~exist(newFolderPath, 'dir')
mkdir(newFolderPath);
end
% Get field names from the struct
fieldNames = fieldnames(mainStruct);
% Loop through each field in the struct
for fieldIdx = 1:length(fieldNames)
fieldName = fieldNames{fieldIdx};
fieldData = mainStruct.(fieldName);
% Create a CSV file for each field
csvFileName = [fieldName '.csv'];
csvFilePath = fullfile(newFolderPath, csvFileName);
% Write the field data to a CSV file
writematrix(fieldData, csvFilePath);
end
end
Please go through the documentation of “dir”, “fieldnames” and “writematrix” functions for better understanding.
I hope this will help!

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