Why do I get NaNs when I try to enter characters in my UITABLE object?

Hello,

I have developed a MATLAB App Designer App. As soon as this App is started, certain contents are to be output in a UITable. As soon as I start the app, all string variables outputs are NaN. I don't understand why these variables are converted to numeric data and how I can work around this. I have already read other forum posts regarding this but could not solve my problem with them.

 % Function Cores Tabelle einrichten
            app.UITable.ColumnWidth = {250,100,558,50};
            
            % Alle Function Cores finden
            fprintf('Searching for Function Cores ...\n');
            content = dir(app.mevtool_functioncores);
            dirFlags = [content.isdir];
            subFolders = content(dirFlags);
            subFolderNames = {subFolders(3:end).name};
            app.valid_function_cores = 0;
            for k = 1 : length(subFolderNames)
                
                function_core_path = fullfile(app.mevtool_functioncores, subFolderNames{k});
                function_core_xml_path = fullfile(function_core_path, 'function_core.xml');
                
                if ~exist(function_core_xml_path)
                    warning('The following directory has no "function_core.xml" file: %s', function_core_path)
                    warning('Discard following Function Core: %s', subFolderNames{k})
                    continue;
                else
                    app.valid_function_cores = app.valid_function_cores + 1;
                    xml_struct = readstruct(function_core_xml_path);
                    app.struct_function_cores(app.valid_function_cores, 1) = string(xml_struct.name);
                    app.struct_function_cores(app.valid_function_cores, 2) = string(xml_struct.version);
                    app.struct_function_cores(app.valid_function_cores, 3) = string(xml_struct.description);
                    app.struct_function_cores(app.valid_function_cores, 4) = "Start";
                end
            	fprintf('Function Core #%d = %s\n', k, subFolderNames{k});
            end
            app.UITable.Data = app.struct_function_cores;

[Ozan Anli]

Example Output:

[Stephen23]

As an aside, regarding this indexing:

subFolderNames = {subFolders(3:end).name};

https://www.mathworks.com/matlabcentral/answers/484430-using-struct-dir-selpath-what-do-and-mean-as-struct-name#answer_395754

https://www.mathworks.com/matlabcentral/answers/40949-omitting-pointers-when-listing-folder-contents#answer_50568

https://www.mathworks.com/matlabcentral/answers/13978-list-of-files-sorting#answer_19278

As Walter Roberson wrote in that last link: "In short: if your code assumes that '.' and '..' are the first two entries in a directory, your code has a bug (even in MS Windows). If your code assumes that directory entries are returned in any sorted order, your code has a bug (in all OS.)"

The robust approach is to use SETDIFF or ISMEMBER or similar on the file/folder names.

[Ozan Anli]

Adjusted the code, ty for the Info!

Answer 1

[Kevin Holly]

Here is a quick workaround. Before loading data into the UITable, you can run the command below to make all the columns strings by default.

app.UITable.Data = " ";

Then when you input data, all of it will be strings. You can convert the string data to numeric with str2num.

[Ozan Anli]

Hello,

unfortunately this workaround does not cause the UITable to output the stings correctly for me.

[Stephen23]

"unfortunately this workaround does not cause the UITable to output the stings correctly for me."

Please show the code where you first create the table.

[Ozan Anli]

% Callbacks that handle component events

methods (Access = private)

% Code that executes after component creation

function startupFcn(app)

% Aktueller Speicherort der APP herausfinden

[app.mevtool_dir,~,~] = fileparts(mfilename('fullpath'));

app.mevtool_functioncores = fullfile(app.mevtool_dir, 'Function_Core');

app.mevtool_utils = fullfile(app.mevtool_dir, 'Utils');

app.WS_Info.Text = strcat('MEVTool Workspace:', {' '}, app.mevtool_dir);

% Function Cores Tabelle einrichten

app.UITable.Data = " ";

app.UITable.ColumnWidth = {250,100,558,50};

This is the beginning of the startupFcn. The first code according to the UITable is following line:

app.UITable.Data = " ";