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

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Ozan Anli
Ozan Anli 2023-3-23
评论： Ozan Anli 2023-3-30
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;
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Stephen23
Stephen23 2023-3-27
编辑：Stephen23 2023-3-27
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.

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回答（1 个）

Kevin Holly
Kevin Holly 2023-3-24
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.
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Stephen23
Stephen23 2023-3-27
"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
Ozan Anli 2023-3-28
% 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 = " ";

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