Changing the Number of Rows in imported Table via Edit-Field in App Designer

in Matlab App Designer, I'm building an App which imports a .csv.

I've added a Numeric Edit Field in which is displayed the Number of Rows of the Imported Table.

                   app.RowsEditField.Value = size(ImportedTable,1);

I would like to make this Edit Field interactive, so that whatever Number I type into that EditField, the Imported Table will be modified to have that number of rows.

If I change the Value to one smaller than the displayed number of Rows, can I make this 'chop' off the corresponding number of Rows in the Table?

If the Imported Table has 100 Rows, and the EditField displays '100', and I change that to 80, I'd like the App to then chop off 20 Rows, let's say the 20 first Rows, of the imported Table.

When I enter a Number greater than the number of Rows in the imported Table, it should simply reset my input to the number of rows, e.g. when I type 250 into the EditField, it should simply jump straight back at displaying 100, not add 150 rows into the Table.

Thank you most kindly in advance!

Answer 1

[Vedant Shah]

Hi @William Collants,

To make the Numeric Edit Field interactive, we need to add a callback function. The desired functionality is as follows: if the value in the Numeric Edit Field is less than or equal to the total number of rows in the table, the table will be modified to display only the specified number of rows by removing the initial extra rows. If the specified number of rows exceeds the total number of rows in the table, the table will display all rows, and the Numeric Edit Field will update to reflect the total number of rows present in the table.

The following Implementation steps can be followed:

First, add two private properties to manage the imported data and the total number of rows:

properties (Access = private) 
    ImportedTable 
    TotalRows 
end

Implement the“startupFcn”to load the entire table when the app is launched:

function startupFcn(app) 
    % Read the CSV file into a table 
    app.ImportedTable = readtable("yourcsvfile.xlsx"); 
    app.UITable.Data = app.ImportedTable; 
    app.TotalRows = size(app.ImportedTable, 1); 
    
    % Update the Numeric Edit Field with the number of rows 
    app.EditField.Value = size(app.ImportedTable, 1); 
end 

Then, add a callback function for the Numeric Edit Field to achieve the intended functionality:

function RowsEditFieldValueChanged(app, event) 
    newRowCount = app.EditField.Value; 
    
    % Check if the new row count is less than the current row count 
    if newRowCount < app.TotalRows 
        app.UITable.Data = app.ImportedTable((app.TotalRows - newRowCount + 1):end, :); 
    elseif newRowCount > app.TotalRows 
        app.EditField.Value = app.TotalRows; 
        app.UITable.Data = app.ImportedTable; 
end

This makes the app work as intended. Below is a screenshot demonstrating the app's functionality: