A table variable name subscript must be a character vector

What does my error mean? i am trying to upload a ".xls" file using "add button"and transfer the data into a table and "add button" will calculate for stress and strain and plot in UI.axes

        % Button pushed function: AddButton
        function AddButtonPushed(app, event)
            strain = app.StrainEditField.Value;
            stress = app.StressEditField.Value;
            nr = {strain, stress};
            app.UITable.Data = [app.t;nr];
        end

        % Button pushed function: PlotButton
        function PlotButtonPushed(app, event)
            app.t = readtable('BlankSheet.xlsx','Sheet',1);
            strain = table2array(app.t(:,""));   %A table variable name subscript must be a character vector, string array, or cell array of character vectors.
            stress = table2array(app.t(:,""));
            plot(app.UIAxes,strain,stress);
        end
    end

Answer 1

[Ameer Hamza]

You need to write the name of column

strain = table2array(app.t(:,"strain_column_name"));   %A table variable name subscript must be a character vector, string array, or cell array of character vectors.
stress = table2array(app.t(:,"stress_column_name"));

Also, you can avoid table2array to array by using brace indexing

strain = app.t{:,"strain_column_name"};   %A table variable name subscript must be a character vector, string array, or cell array of character vectors.
stress = app.t{:,"stress_column_name"};

[sydney salvador]

I am sorry I do not know the name of my column or how/where to place a name for it, this is the file i use

I only have a name for the whole table

  properties (Access = private)
        t % Table to share between callbacks
    end

[Ameer Hamza]

sydney, columns in MATLAB tables must have a name. If you don't specify, then still MATLAB gives them a default name. For example, when I run these lines using your file

t = readtable('BlankSheet.xlsx','Sheet',1);
disp(t)

    Var1    Var2
    ____    ____
     0       2  
     5       2  
     6       4  

The column names are Var1 and Var2. If the column had names in excel files, then MATLAB would have used those names. So to access the first Var1 column, you need to write it like this

strain = t{:,"Var1"};
stress = t{:,"Var2"};

You can also directly use the column number if you are confused about the name of column

strain = t{:,1};
stress = t{:,2};

[Walter Roberson]

t{:, 2} for stress

[Ameer Hamza]

Thanks for pointing out.