"Unable to update data tip using custom update function"

Hey guys, when I make the custom text function for dataCursorMode it keeps on showing this when clicking on the marker on the plot

Here is the code for the plot

function WinChampgraph_team_selector
    data2 = readtable("alltimeteams.xlsx",'VariableNamingRule','preserve');
    
    % Calculate the win percentage for each team
    winPercent = (data2.Wins ./ (data2.Wins + data2.Losses));
    
    hold on
    
    graph = plot(winPercent, data2.Championships,"LineStyle","none","Color","r","Marker","*");
    
    dcm = datacursormode;
    dcm.Enable = 'on';
    dcm.UpdateFcn = @displayteam;
    getCursorInfo(dcm);
    
    displayteam(data2);
    
    xlabel('Win Percentage');
    ylabel('Championships');
    title('Team performance since the beginning of the NBA');
    grid on;
    set(gcf,'Position',[50,500,700,500])
     
end

Here is the code for the custom text function

function txt = displayteam(data3)
    x = data3.Franchise;
    
    y = (data3.Wins ./ (data3.Wins + data3.Losses));
   
    myDatatipText = "(%s, %s, %s)";   
    txt = sprintf(myDatatipText, string(x), string(y),data3.Championships);
end

Then it shows this on the plot

Unable to update data tip using custom update function

Please lmk is anything else is needed

Answer 1

[Stephen23]

Solution One

Replace

dcm.UpdateFcn = @displayteam;

with

dcm.UpdateFcn = @(~,~)displayteam(data2);

Explanation

The property UpdateFcn is called with two input arguments, as its documentation explains:

https://www.mathworks.com/help/matlab/ref/matlab.graphics.shape.internal.datacursormanager.html#mw_814d9981-fc1f-41e1-b067-da71a221c4d7

Instead of following the documentation you have provided one input argument in the function signature, which is a table (and not either of the inputs specified in the UpdateFcn documentation). So to provide your desired input table we can simply define the UpdateFcn as an anonymous function which accepts (and ignores) the two documented inputs and passes your table:

https://www.mathworks.com/help/matlab/creating_guis/write-callbacks-for-apps-created-programmatically.html#bvf4jbn

Solution Two

You will then notice that every data tip is exactly the same. That is because the displayteam function has no way to distinguish what data point was clicked on. So if you want the datatips to be different then you need to modify displayteam to e.g. also include the info structure...

For example use

dcm.UpdateFcn = {@displayteam,data2};

https://www.mathworks.com/help/matlab/creating_guis/write-callbacks-for-apps-created-programmatically.html#brqow8p

and define the function to accept all three inputs:

function txt = displayteam(~,info,data3)

and inside displayteam you can then use the values of

info.Position

and/or

info.Index

to match to your imported table data. As I have no idea what logic you want to implement I will leave that up to you.

[Ayaan]

Sorry but where does

info.Position

fit into the code?

[Stephen23]

"Sorry but where does info.Position fit into the code?"

Most likely inside displayteam (i.e. where you write the code that determines what to display). For example:

function txt = displayteam(~,info,data3)
idx = info.DataIndex;  % index of the clicked point
fnm = data3.Franchise{idx}; % curly brace indexing
wpc = data3.Wins(idx) ./ (data3.Wins(idx) + data3.Losses(idx));
cnt = data3.Championships(idx);
txt = sprintf("(%s, %g, %d)", fnm, wpc, cnt);
end

[Ayaan]

I see, but what is the method to get the index of the clicked point?

[Stephen23]

"I see, but what is the method to get the index of the clicked point?"

From the 2nd input of the UpdateFcn callback function:

info.DataIndex

Its value is generated by MATLAB when you click on a point. You just need to use it:

function txt = displayteam(~,info,data3)
idx = info.DataIndex;  % index of the clicked point
fnm = data3.Franchise{idx}; % curly brace indexing
wpc = data3.Wins(idx) ./ (data3.Wins(idx) + data3.Losses(idx));
cnt = data3.Championships(idx);
txt = sprintf("(%s, %g, %d)", fnm, wpc, cnt);
end

[Ayaan]

The code is working and it is showing what i wanted but it is still coming up with an error?

Here is the new code for the plot

data2 = readtable("alltimeteams.xlsx",'VariableNamingRule','preserve');
 
    
    hold on
    winPercent = (data2.Wins ./ (data2.Wins + data2.Losses)); % Calculate the win percentage for each tea
    plot(winPercent, data2.Championships,"LineStyle","none","Color","r","Marker","*"); % plots graph of championships against total win percentage
    xlabel('Win Percentage');
    ylabel('Championships');
    title('Team performance since the beginning of the NBA');
    grid on;
    set(gcf,'Position',[50,500,700,500])
    
    dcm = datacursormode;
    dcm.Enable = 'on'; % switches on datacursormode
    dcm.UpdateFcn = {@displayteam,data2};
    displayteam(data2);
    getCursorInfo(dcm);

and the code for the function is the same as yours.

Here is the error

    Not enough input arguments.

Error in displayteam (line 2)
    idx = info.DataIndex;  % index of the clicked point
          ^^^^^^^^^^^^^^
Error in WinChampgraph_team_selector (line 16)
    displayteam(data2);
    ^^^^^^^^^^^^^^^^^^
Error in Main_script (line 16)
    WinChampgraph_team_selector()
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

I think it is something to do with calling the fucntion but i cant figure out what

[Stephen23]

Delete this line:

displayteam(data2);

In my lastest code here

https://www.mathworks.com/matlabcentral/answers/2181579-unable-to-update-data-tip-using-custom-update-function#comment_3345804

the function signature was modified to require three input arguments. However on that line you call it with one input only, thus the error. Note that the line returns a text output which you ignore and discard, so that line is completely superfluous anyway. Simplest solution: get rid of that line.

[Ayaan]

Great, thank you!