How can I initiate a while loop with a GUI button (using UI control) and then end that loop with a different GUI button?
8 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
I am working with a tracking system and I have been using a while loop to continuously scan for data. The whole time I have been terminating the loop with control-c, but now I am manipulating an old GUI and trying to initiate and terminate the loop with buttons in the GUI. I thought this might work but I am not having any luck:
%pivot shift button %collects data while subject performs pivot shift PS_data = uicontrol('Position',[1125 250 100 25],'String','Pivot Shift', 'FontSize',12,'Callback','GUI_data_collection'); %calls data collection
%This ends the pivot shift PivotShiftEndButton = uicontrol('Position',[1125 200 100 25],'String','End Shift',..., 'FontSize',12,'Callback','delete(PS_data)');
fprintf(Ftrak,'C'); shift_data = [];
while ishandle(PS_data)
scan = fscanf(Ftrak,'%f');
scan= scan';
if length(scan) == 7
shift_data = [shift_data;scan];
if shift_data(end,1) == shift_data(end - 1,1)
shift_data(end,:) = [];
end
end
end
1 Kommentar
Jan
am 1 Aug. 2017
Please use the "{} Code" button to format you code, such that it becomes readable. Then explain "not having any luck" with details. It is easier to fix a problem than to guess, what the problem is.
Akzeptierte Antwort
Jan
am 1 Aug. 2017
Bearbeitet: Jan
am 1 Aug. 2017
Do not use a string to define a callback. This is supported for backward compatibility with the ancient Matlab 5.3 only. Use a function handle instead:
...'Callback', @GUI_data_collection
'delete(PS_data)' is a bad callback also: Remember that callbacks, which are defined as strings, are evaluated in the base workspace. There PS_data is unknown. Better use a flag stored in the GUI:
PivotShiftEndButton = uicontrol('Position',[1125 200 100 25],'String','End Shift',...,
'Callback', @StopDataCollection, ...
'UserData' 1); % <-- The flag
fprintf(Ftrak,'C');
shift_data = [];
while get(PivotShiftEndButton, 'UserData')
scan = fscanf(Ftrak,'%f').';
if length(scan) == 7
shift_data = [shift_data;scan];
if shift_data(end,1) == shift_data(end - 1,1)
shift_data(end,:) = [];
end
end
drawnow; % Give the GUI a chance to update
end
function StopDataCollection(hObject, EventData)
set(hObject, 'UserData', 0);
end
Note that the iterative growing of the array uses a huge amount of resources. In each iteration 7 elements a 8 bytes are appended. Therefore a new array is created an the old values are copied. for 10'000 iterations, this does not allocate 10'000*56 bytes=560kB, but sum(1:10000) * 56 bytes: 2.8 GB!
Better pre-allocate the output with a maximum number of recorded data. Although such a limit is a drawback, the current method is limited by exhausting the computer until it crashs.
5 Kommentare
Jan
am 5 Aug. 2017
You can fix the value of the UserData by setting them:
set(PivotShiftEndButton, 'UsersData', 1);
I do not know where this must be inserted, because I do not know the complete code for this GUI. Perhaps before the loop or after it, maybe in a callback.
Weitere Antworten (0)
Siehe auch
Kategorien
Mehr zu Loops and Conditional Statements finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!