How to add data to cursor tip, BUT each piece of data is from a separate computation or table lookup. (Not the idx, not the coordinates.)

This works except ... not sure how to get the data I want to show in the 'Payoff' label at the data point.

If you can solve this, genius. I really appreciate your help. DC

% Curse02.m
% Add data to where the cursor point is on a figure.
clearvars; close all; clc;
% Example data
x = 1:10;
y = randi([1, 20], 1, 10);
% Here I just created 10 random numbers to use as an example of the data I
% want to show at the cursor tip on hover-over. These values could be stored in a table or generated in real time by a function I use to generate them.  I tried to put these into the 'extraInfo' but that is where I fail.
for i = 1:length(x)
    Payoff(i) = rand;
end
% Create a figure and plot the data
figure(1);
plot(x, y, 'marker','o','MarkerSize',20,'MarkerEdgeColor','g','linestyle','none');
xlabel('X-axis');
ylabel('Y-axis');
title('Data Cursor with Additional Information');
hold on
% add index labels to the plot
for i = 1:length(x)
    text(x(i), y(i), num2str(i), 'HorizontalAlignment', 'center')
end
% Define the data cursor
dcm_obj = datacursormode(gcf);
set(dcm_obj, 'UpdateFcn', @myDataCursorCallback); % Set the callback function
% Callback function to display additional information
function txt = myDataCursorCallback(~, event_obj)
pos = get(event_obj, 'Position');
idx = get(event_obj, 'DataIndex');

% Additional information to display
% This labels correctly but puts the index value and not the payoff.
extraInfo = ['A= ', num2str(pos(1)), ', B= ', num2str(pos(2)),...
    'Payoff: ', num2str(idx)];
% Instead of index, display the payoff.

% Construct the text to display
txt = {['D:',' ', extraInfo]};
end

Answer 1

[Voss]

One way to do that is to use the array Payoff as an input to myDataCursorCallback. Something like this:

% Curse02.m
% Add data to where the cursor point is on a figure.
clearvars; close all; clc;
% Example data
x = 1:10;
y = randi([1, 20], 1, 10);
% Here I just created 10 random numbers to use as an example of the data I
% want to show at the cursor tip on hover-over. These values could be stored in a table or generated in real time by a function I use to generate them.  I tried to put these into the 'extraInfo' but that is where I fail.
Payoff = rand(1,numel(x));
% Create a figure and plot the data
figure;
plot(x, y, 'marker','o','MarkerSize',20,'MarkerEdgeColor','g','linestyle','none');
xlabel('X-axis');
ylabel('Y-axis');
title('Data Cursor with Additional Information');
hold on
% add index labels to the plot
text(x, y, compose('%d',1:numel(x)),'HorizontalAlignment', 'center')
% Define the data cursor
dcm_obj = datacursormode(gcf);
set(dcm_obj, 'UpdateFcn', {@myDataCursorCallback,Payoff}); % Set the callback function, and include additional argument Payoff


% Callback function to display additional information
function txt = myDataCursorCallback(~, event_obj, extraData)
    pos = get(event_obj, 'Position');
    idx = get(event_obj, 'DataIndex');
    
    % Additional information to display
    % This puts the the payoff, which has been sent as input extraData 
    extraInfo = ['A= ', num2str(pos(1)), ', B= ', num2str(pos(2)),...
        ', Payoff: ', num2str(extraData(idx))];
    
    % Construct the text to display
    txt = {['D:',' ', extraInfo]};
end

[David]

Thanks Voss, this works and gives me a better understanding of how that data tip object works. I really appreciate your working on this. Genius ++

[Voss]

You're welcome!