App Designer: Error using readtable "filename" must be a string scalar or character vector.

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Connor Fitzgerald 2021-1-14

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https://ww2.mathworks.cn/matlabcentral/answers/717400-app-designer-error-using-readtable-filename-must-be-a-string-scalar-or-character-vector

评论： Cris LaPierre 2021-1-14

采纳的回答： Cris LaPierre

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Hello,

Please help me to resolve this issue I've been struggling with for hours on end.

My goal is to use multiselect to select several files and import them as tables to be manipulated independently via the GUI

app.ListBoxFileNames.Items = fileList
app.ListBoxPlotNames.Items
[file, path] = uigetfile('*.*','MultiSelect','on')
if noFiles == 1 % Code works for 1 file
     initTable = readtable(file);       % init table I think work with in the GUI
    
     app.ListBoxFileNames.Items = fileList;   % this is a cell
     app.ListBoxPlotNames.Items = fileList;
                 
else % Issues when using multiselect
    for i=1:numel(file) 
      fileListNew = fileList(:,i)
      
      % Below I try to use a structArray to contain a structure consisting of all the tables I import, as I don't know how else to work with the multiple tables
      structArray(i) = table2struct(readtable((fileListNew))) % structArray(i)'s I would also like to work with independently in the GUI as separate tables.
      app.ListBoxFileNames.Items{i} = fileList;
      app.ListBoxPlotNames.Items{i} = fileList;
    end
end

Any meaningful assistance would be appreciated. Thank you.

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Cris LaPierre 2021-1-14

include the full error message (all the red text)

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Answer 1

Cris LaPierre 2021-1-14

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https://ww2.mathworks.cn/matlabcentral/answers/717400-app-designer-error-using-readtable-filename-must-be-a-string-scalar-or-character-vector#answer_598315

编辑：Cris LaPierre 2021-1-14

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I suspect the error is with how you are indexing you file names.

First, what is fileList? Shouldn't you be using the files that were just selected? That's file, which is a cell arry. Try using curly braces to index your cell instead of parentheses.

structArray(i) = table2struct(readtable(file{i}));

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Cris LaPierre 2021-1-14

在 MATLAB Online 中打开

Based on the Command Window error message, it would appear you did not implement the solution I recomended. You are still not indexing file. When you select more than 1 file, you are going to get an error about filename.

Why not simplify a little while you debug. Get this simplified script to load the files correctly in MATLAB first. Then add it to app designer.

I'm not suprised about the assignment error. Look at the syntax options for table2struct. The syntax you are using creates a m-by-1 structure array with n fields. I suspect what you want is a structure with n fields, each of which has m rows. That requires adding the input options 'ToScaler',true to table2struct.

[file, path] = uigetfile('*.*','MultiSelect','on');
file = string(file);
if numel(file) == 1 % Code works for 1 file
     initTable = readtable(file);       % init table I think work with in the GUI
 
else % Issues when using multiselect
    for i=1:numel(file) 
      % Below I try to use a structArray to contain a structure consisting of all the tables I import, as I don't know how else to work with the multiple tables
      structArray(i) = table2struct(readtable(file(i)),'ToScalar',true) % structArray(i)'s I would also like to work with independently in the GUI as separate tables.
    end
end

Connor Fitzgerald 2021-1-14

Just to confirm - my code was exactly as you said so that was not the reason.

I took your advice on simplifying the problem which worked wonders. It seems structs are not good for what I need, due to my tables having different sizes. I have now come to realise that a deeper issue lies in not resizing my table for the second iteration.

Thank you for you time and assistance.

Cris LaPierre 2021-1-14

You might consider a table of tables (see here). However, if you now have a clearer idea of how to organize your data, take the opportunity to do that.

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App Designer: Error using readtable "filename" must be a string scalar or character vector.

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