can a timetable column reference a function handle automatically and dynamically add current value based on a set of computations?

Reviving this question.

Adding data: can always be done through adding a new column by referencing a function, such as:

timeTable.Data = functionOf(timeTable.ExistingVar);

But this is static. What if we could do this automatically when an event happens (add value/edit value) ...

Something along the lines of a column that automatically computes best/worst performers (max/min/etc) on all the other columns & does a set of operations based on its previous values ... say something like this:

newValue = previousValue + max(values in columns 1:10) on the last line.

This would also be similar to an excel colum defined with a (simple) formula based on another column(s) value(s). Can this be achieved through any Matlab construct / object?

thx

Answer 1

[Abhinaya Kennedy]

Hi Andy,

As I understand, you would like to achieve dynamic updates to a table or array. One way to achieve this is using event listeners and callback functions. MATLAB does not have a built-in feature that exactly replicates Excel's cell formula functionality, but you can simulate it by creating a function that updates your table when certain events occur.

To implement this, you can use MATLAB's event handling capabilities with its property listener functionality. Here's a conceptual example of how you could set up a MATLAB class that updates a table's column automatically when data in other columns change.

First, you would define a MATLAB class that contains the table and the methods to update it:

classdef DynamicTable < handle
    properties
        Data table
    end
    
    methods
        function obj = DynamicTable(initialData)
            obj.Data = initialData;
            % Set up listeners for each variable in the table
            for varName = initialData.Properties.VariableNames
                addlistener(obj.Data, varName{1}, 'PostSet', @(src, event)obj.updateColumn());
            end
        end
        
        function updateColumn(obj)
            % Define the operation for the new value
            % Assuming the last line is the one that changes
            lastRow = height(obj.Data);
            previousValue = obj.Data{lastRow, 'ComputedColumn'};
            maxValue = max(obj.Data{lastRow, 1:10}, [], 2); % max across columns 1 to 10
            newValue = previousValue + maxValue;
            obj.Data{lastRow, 'ComputedColumn'} = newValue; % Update the computed column
        end
    end
end

To use this class, first initialize your table with the initial data, and then create an instance of `DynamicTable`:

% Example initial data
initialData = array2table(rand(10), 'VariableNames', {'Var1', 'Var2', 'Var3', 'Var4', 'Var5', 'Var6', 'Var7', 'Var8', 'Var9', 'Var10'});
initialData.ComputedColumn = zeros(10, 1); % Initialize the computed column

% Create an instance of the DynamicTable class
dynamicTable = DynamicTable(initialData);

Now, whenever you change the data in the first 10 columns of `dynamicTable.Data`, the `updateColumn` method will be called automatically to update the 'ComputedColumn'.

Please note that this example assumes that the last row is the one that is being updated. You would need to adjust the logic in the `updateColumn` method if changes can occur in rows other than the last one, or if multiple rows can be updated at once.

Hope this helps.