IF statement not executing

        % Value changed function: ActionDropDown_2
        function ActionDropDown_2ValueChanged(app, event)
            if app.ActionDropDown_2.Value == "Plot"               
               app.Tbl = app.UITable2.Data(:,{'DATE', 'AVAILABILITY'});
               app.X = app.UITable2.Data(:,3);
               app.Y = app.UITable2.Data(:,31);
               plot(app.UIAxes,app.X,app.Y)
            end
        end

The callback function operates as expected, once called, the debug arrow reaches breakpoint of the IF statment line but once I chose to "Continue" the debug arrow jumps straight to END. Not executing any of the following lines to define Tbl, X, or Y and no plot.

[shnrndll]

Data is an x by 31 table, the table holds several variables but the relevant variables are DATE, 3rd column and, AVAILABILITY, 31st column

[Voss]

Seems like app.ActionDropDown_2.Value is not equal to "Plot".

[shnrndll]

Yes, but why is of question, the line of code seems correct

[Cris LaPierre]

The code is syntatically correct, and you are not getting any errors. The issue is that the condition evaluates as false, so the code inside the statement does not get run.

[shnrndll]

Well the IF condition line equates to Plot, during debugging, the breakpoint of this line displayed ".Value" equating to Plot

[Walter Roberson]

Put a breakpoint at the if. When you arrive there, command

class(app.ActionDropDown_2.Value)
if char(app.ActionDropDown_2.Value)
   disp('char')
   disp(double(app.ActionDropDown_2.Value))
elseif isstring(app.ActionDropDown_2.Value)
    disp('string')
    disp(double(app.ActionDropDown_2.Value{1}))
else
    disp('other')
    disp(app.ActionDropDown_2.Value)
end

and tell us what the output is.

This is not intended as permanent code: it is only intended to help debug the problem.

Answer 1

[Image Analyst]

You need to check the index of the drop down list, or else get the selected string and compare the that string (only) to "Plot" using the contains() function:

% Value changed function: ActionDropDown_2
function ActionDropDown_2ValueChanged(app, event)
% Check the index of the selected item.
selectedIndex = app.ActionDropDown_2.Value;

% Method #1:
%if selectedIndex == 3 % or whatever number in the list it is.
% Rest of "if" block follows...

% Or use Method #2:
% Check the selected string.  First get all strings in the list.
allStrings = app.ActionDropDown_2.String;
% Get the specific one that was selected.
selectedString = allStrings{selectedIndex};
% See if it says "Plot".
if contains(selectedString, "Plot", 'IgnoreCase', true)
    % They chose plot, so do the plotting.
    app.Tbl = app.UITable2.Data(:,{'DATE', 'AVAILABILITY'});
    app.X = app.UITable2.Data(:,3);
    app.Y = app.UITable2.Data(:,31);
    plot(app.UIAxes,app.X,app.Y)
end
end

[shnrndll]

Please see https://www.mathworks.com/matlabcentral/answers/1622860-if-statement-not-executing#comment_1920545

[Image Analyst]

What do you notice if we simplify it to

app.X = app.UITable2.Data(:,3);
app.Y = app.UITable2.Data(:,31);
whos app.X % Look in command window for this
whos app.Y % Look in command window for this
app.s = scatter(app.X, app.Y); % Might plot in some different axes control though

What do you see in the command window, and on your GUI? The data types should be there inthe command window, plus any error messages.

[shnrndll]

Thank you I solved this with you code