How to find variable strings within a structure?

Hi! I have a workspace variable named 'simulation' which houses 6 fields. These fields have a varying number of fields within them. Is it possible to search every 'branch' of this 'simulation' structure to find string values that contain '.m'?

For example, to find that:

simulation.system{1, 1}.system{1, 1}.system{1, 1}.initialization{1, 1}.name

contains the string 'drv_ctrl_look_ahead_init.m'

Answer 1

[Deepak]

Hi @Adam R,

We can search through a nested structure in MATLAB to find string values containing '.m' by implementing a recursive function that traverses each level of the structure. The function, "findMFilesInStruct", iterates over each field, checking if it is a structure, a cell array, or a string. If it encounters a structure, it recursively calls itself to delve deeper. For cell arrays, it iterates through each element, and for strings, it uses the "contains" function to check for '.m'. When a match is found, it prints the path to the console, allowing us to locate all instances of strings containing '.m' within the complex structure.

Below is the sample MATLAB code to achieve the same:

function findMFilesInStruct(structVar, parentPath)
    % Loop over each field in the structure
    fields = fieldnames(structVar);
    for i = 1:length(fields)
        fieldName = fields{i};
        fieldValue = structVar.(fieldName);
        
        % Construct the current path
        currentPath = strcat(parentPath, '.', fieldName);
        
        % Check if the field is a structure itself
        if isstruct(fieldValue)
            % Recursively search the sub-structure
            findMFilesInStruct(fieldValue, currentPath);
        elseif iscell(fieldValue)
            % If the field is a cell array, iterate through its contents
            for j = 1:numel(fieldValue)
                if isstruct(fieldValue{j})
                    % Recursively search the sub-structure
                    findMFilesInStruct(fieldValue{j}, strcat(currentPath, '{', num2str(j), '}'));
                elseif ischar(fieldValue{j}) && contains(fieldValue{j}, '.m')
                    % Check if the string contains '.m'
                    fprintf('Found .m file in: %s{%d}\n', currentPath, j);
                end
            end
        elseif ischar(fieldValue) && contains(fieldValue, '.m')
            % Check if the string contains '.m'
            fprintf('Found .m file in: %s\n', currentPath);
        end
    end
end

findMFilesInStruct(simulation, 'simulation');

Please find attached the documentation of functions used for reference:

strcat: www.mathworks.com/help/matlab/ref/strcat.html

isstruct: www.mathworks.com/help/matlab/ref/isstruct.html

contains: www.mathworks.com/help/matlab/ref/string.contains.html

I hope this assists in resolving the issue.