Hi, Yes and no. If you just copied your entire code into the __init__ method of a Widget, it would behave exactly the same (the DE solving loop would block up the init, so UI wouldn't be completed until after it finished). You would still need to either trigger single iterations of the loop with a timer as I think you have done, which lets the UI update work proceed in between, or do it multithreaded as per the link I posted, where your DE solving loop would be doing its own thing in the separate generate_data() thread, but you do the callback(data) once each time the solution updates, which will then trigger the redraw of the UI in its own thread.
Patrick On Tuesday, 2 April 2019 23:44:24 UTC+10:30, Michael DeFeo wrote: > > Hi Patrick, > > Thank you for the explanation. I will read through the thread you linked > to. I have been using pyqtgraph for various things for a couple of > years--it is probably time I learn about the Qt event loop. If I were to > make my script into a class and instance the class after 'if __name__ == > '__main__': would the plotting have worked as expected since the timer > would start prior to solve the DE? > > Cheers, > Mike > > On Sunday, March 31, 2019 at 6:30:37 PM UTC-6, Patrick wrote: >> >> Hi, >> >> I thought an explanation of why your original code didn't work might be >> helpful. Since pyqtgraph is based off Qt, then understanding the Qt event >> loop is important - all of the GUI updates must be done from within the Qt >> event loop. Data acquisition or processing can be done on separate threads, >> but should be communicated back to the GUI through Qt signal/slot style >> methods. >> >> In your code, your program starts up and does the DE solving code >> immediately. Interestingly, your timer.start() call doesn't actually start >> the timer yet! Your program then hits the __name__ == '__main__' part, >> where the .exec_() line starts the Qt event loop thread. This then begins >> triggering events, such as displaying the GUI and starting the timer calls. >> So by the time your GUI is drawn, the DE solving is done. >> >> Jim's answer above is correct. If you're interested in doing this the >> alternative way, processing on a separate thread (and doing the >> signal/slots thing), then the code from this answer might help explain how >> to do that: >> https://groups.google.com/forum/#!msg/pyqtgraph/ajykxBvysEc/e1V8lvZSCgAJ >> >> Patrick >> >> >> On Sunday, 31 March 2019 06:29:45 UTC+10:30, Michael DeFeo wrote: >>> >>> Thank you very much for your reply. I was able to get it working by >>> using QTimers to call the functions that evaluate the ODE as you suggested. >>> >>> Cheers, >>> Mike >>> >>> On Thursday, March 28, 2019 at 11:48:03 AM UTC-6, Michael DeFeo wrote: >>>> >>>> I am trying to write a program that will solve a differential equation >>>> for several values of one of the equations parameters in a for loop. After >>>> each iteration of the loop I would like to plot the mean value of the >>>> solution. What happens in practice is the the plot will only be generated >>>> after exiting the for loop. A minimal working example demonstrating this >>>> issue is pasted below and attached. Any advice on how to get this working >>>> is appreciated. >>>> >>>> Cheers! >>>> >>>> >>>> >>>> # gui >>>> import pyqtgraph as pg >>>> from pyqtgraph.Qt import QtCore, QtGui >>>> import numpy as np >>>> >>>> # ODE >>>> from scipy.integrate import RK45 >>>> >>>> win = pg.GraphicsWindow() >>>> p1 = win.addPlot() >>>> data = np.empty([100000,2]) # Holds time dep. solution >>>> >>>> g = 0.5 >>>> cntr = 0 >>>> >>>> def EOM(t,y): >>>> global g >>>> return -g*y >>>> >>>> def update(): >>>> p1.plot(tcData[:cntr,:]) >>>> >>>> timer = QtCore.QTimer() >>>> timer.timeout.connect(update) >>>> timer.start(0) >>>> >>>> tC = np.linspace(-0.5,0.5,20) # Sweep parameter >>>> tcData = np.empty([len(tC),2]) # Holds mean solution (plot this data) >>>> for idx,item in enumerate(tC): >>>> ode = RK45(EOM, 0, [5],t_bound=10,max_step=0.001) >>>> cntr = 0 >>>> g = item >>>> while ode.status == 'running': >>>> ode.step() >>>> data[cntr,0] = ode.t >>>> data[cntr,1] = ode.y >>>> cntr+=1 >>>> tcData[idx,0] = item >>>> tcData[idx,1] = np.mean(data[:,1]) >>>> print( idx ) >>>> >>>> >>>> if __name__ == '__main__': >>>> import sys >>>> if (sys.flags.interactive != 1) or not hasattr(QtCore, >>>> 'PYQT_VERSION'): >>>> QtGui.QApplication.instance().exec_() >>>> >>>> -- You received this message because you are subscribed to the Google Groups "pyqtgraph" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/pyqtgraph/f3a2d0b8-744b-41ea-9620-1512382789ba%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
