sound interesting but, how do you use QProcess, what I have read about it is that this class is for executing external applications (yes, processes), how to use QProcess in a pool. Could you tell me more about HDF5, for example, how do you use it with python. My dataset could be very big (or what I think is big), for example, a serie of 1500 dicom images so I think that HDF5 could be useful to me.
On Mon, May 9, 2011 at 9:24 AM, Belzile Marc-André <[email protected]> wrote: > As an alternative to python multiprocessing module, I'm using QProcess for > loading and exporting files with my own pool manager. It's pretty darn fast > and works well, my data sets are managed with HDF5 which takes care of > handling huge data sets pretty easily. If you want to pass data back to the > UI you can use QSharedMemory to give the GUI access to your data. > Check out my project for a QProcess example. > http://code.google.com/p/ice-cache-explorer/ > > -mab > "The world goin' one way, people another!" - Poot > > > >> Date: Mon, 9 May 2011 09:10:20 -0400 >> From: [email protected] >> To: [email protected] >> CC: [email protected] >> Subject: Re: [PyQt] pyqt4 amd multiprocessing >> >> I am very interested in the answer because I have plan to use >> multiprocessing module to do my hard work (because of the python GIL), >> my future design is something like Samuele say, a pool of process >> ready to do some hard job (using multiprocessing) and the GUI with >> pyqt4 and vtk, data pass back and forth between the gui and the worker >> processes (data will be vtk datasets) >> >> On Mon, May 9, 2011 at 6:26 AM, Samuele Carcagno <[email protected]> >> wrote: >> > Hi, >> > >> > I would like to use the multiprocessing module to create a set of sounds >> > (as numpy arrays) in parallel. >> > The parameters of the sounds (duration, volume, etc..) are controlled by >> > a pyqt4 GUI, and the sounds >> > need to be passed back to the GUI for further processing and >> > presentation. The sounds are generated >> > in a separate module from the GUI. I'm attaching a minimal example with >> > a file that creates the gui and >> > a second file that contains the functions for generating the sounds. >> > >> > I've had mixed success so far, it seems to work on Kubuntu Natty - >> > Python 2.7.1+ - Qt 4.7.2 - PyQt 4.8.3 >> > but sometimes it fails on Kubuntu Lucid - Python 2.6.5 - Qt 4.6.2 - >> > PyQt 4.7.2 with the following error: >> > >> > Traceback (most recent call last): >> > File "test_gui.py", line 20, in onClickButton1 >> > self.doTrial() >> > File "test_gui.py", line 32, in doTrial >> > x = complexTone(F0, lowHarm, highHarm, level, duration, ramp, >> > channel, fs, maxLevel) >> > File "/media/ntfsShared/mptest/simple_test/stim.py", line 45, in >> > complexTone >> > pool.join() >> > File "/usr/lib/python2.6/multiprocessing/pool.py", line 342, in join >> > p.join() >> > File "/usr/lib/python2.6/multiprocessing/process.py", line 119, in join >> > res = self._popen.wait(timeout) >> > File "/usr/lib/python2.6/multiprocessing/forking.py", line 117, in wait >> > return self.poll(0) >> > File "/usr/lib/python2.6/multiprocessing/forking.py", line 106, in poll >> > pid, sts = os.waitpid(self.pid, flag) >> > OSError: [Errno 4] Interrupted system call >> > >> > Am I doing something fundamentally unsafe by using multiprocessing in >> > this way with a pyqt4 GUI? >> > What is the best approach to use multiprocessing together with pyqt4? >> > >> > Thanks for any suggestions! >> > >> > Sam >> > >> > ###---------GUI----------File 1 >> > from PyQt4 import QtGui >> > from PyQt4 import QtCore >> > import sys >> > from stim import* #import module for stimulus generation >> > >> > >> > class Example(QtGui.QWidget): >> > >> > def __init__(self): >> > super(Example, self).__init__() >> > self.setGeometry(300, 300, 250, 150) >> > self.setWindowTitle('Multiprocessing Test') >> > >> > self.button1 = QtGui.QPushButton('Button 1', self) >> > QtCore.QObject.connect(self.button1, >> > QtCore.SIGNAL('clicked()'), >> > self.onClickButton1) >> > >> > def onClickButton1(self): >> > self.doTrial() >> > >> > def doTrial(self): >> > F0 = 200 >> > lowHarm=1 >> > highHarm = 20 >> > level = 50 >> > duration = 180 >> > ramp = 10 >> > channel = "Both" >> > fs = 44100 >> > maxLevel = 100.0 >> > x = complexTone(F0, lowHarm, highHarm, level, duration, ramp, >> > channel, fs, maxLevel) >> > >> > >> > if __name__ == '__main__': >> > app = QtGui.QApplication(sys.argv) >> > ex = Example() >> > ex.show() >> > app.exec_() >> > #----------END OF FILE 1 >> > >> > >> > ###-SOUND GENERATION-- File stim.py >> > from numpy import* >> > import multiprocessing >> > >> > def pureTone(frequency, phase, level, duration, ramp, channel, fs, >> > maxLevel): >> > >> > amp = 10**((level - maxLevel) / 20.) >> > duration = duration / 1000. #convert from ms to sec >> > ramp = ramp / 1000. >> > >> > nSamples = int(round(duration * fs)) >> > nRamp = int(round(ramp * fs)) >> > nTot = nSamples + (nRamp * 2) >> > >> > timeAll = arange(0., nTot) / fs >> > timeRamp = arange(0., nRamp) >> > >> > snd = zeros((nTot, 2)) >> > >> > if channel == "Right": >> > snd[0:nRamp, 1] = amp * ((1-cos(pi * timeRamp/nRamp))/2) * >> > sin(2*pi*frequency * timeAll[0:nRamp] + phase) >> > snd[nRamp:nRamp+nSamples, 1] = amp* sin(2*pi*frequency * >> > timeAll[nRamp:nRamp+nSamples] + phase) >> > snd[nRamp+nSamples:len(timeAll), 1] = amp * ((1+cos(pi * >> > timeRamp/nRamp))/2) * sin(2*pi*frequency * >> > timeAll[nRamp+nSamples:len(timeAll)] + phase) >> > elif channel == "Left": >> > snd[0:nRamp, 0] = amp * ((1-cos(pi * timeRamp/nRamp))/2) * >> > sin(2*pi*frequency * timeAll[0:nRamp] + phase) >> > snd[nRamp:nRamp+nSamples, 0] = amp* sin(2*pi*frequency * >> > timeAll[nRamp:nRamp+nSamples] + phase) >> > snd[nRamp+nSamples:len(timeAll), 0] = amp * ((1+cos(pi * >> > timeRamp/nRamp))/2) * sin(2*pi*frequency * >> > timeAll[nRamp+nSamples:len(timeAll)] + phase) >> > elif channel == "Both": >> > snd[0:nRamp, 0] = amp * ((1-cos(pi * timeRamp/nRamp))/2) * >> > sin(2*pi*frequency * timeAll[0:nRamp] + phase) >> > snd[nRamp:nRamp+nSamples, 0] = amp* sin(2*pi*frequency * >> > timeAll[nRamp:nRamp+nSamples] + phase) >> > snd[nRamp+nSamples:len(timeAll), 0] = amp * ((1+cos(pi * >> > timeRamp/nRamp))/2) * sin(2*pi*frequency * >> > timeAll[nRamp+nSamples:len(timeAll)] + phase) >> > snd[:, 1] = snd[:, 0] >> > >> > return snd >> > >> > >> > def complexTone(F0, lowHarm, highHarm, level, duration, ramp, channel, >> > fs, maxLevel): >> > pool = multiprocessing.Pool() >> > tn = [] >> > >> > for i in range(lowHarm, highHarm+1): >> > res = pool.apply_async(pureTone, (F0*i, 0, level, duration, ramp, >> > channel, fs, maxLevel,), callback=tn.append) >> > >> > pool.close() >> > pool.join() >> > >> > for i in range(len(tn)): >> > if i == 0: >> > snd = tn[i] >> > else: >> > snd = snd + tn[i] >> > >> > return snd >> > >> > #----------END OF FILE 2 >> > _______________________________________________ >> > PyQt mailing list [email protected] >> > http://www.riverbankcomputing.com/mailman/listinfo/pyqt >> > >> >> >> >> -- >> Lic. José M. Rodriguez Bacallao >> Centro de Biofisica Medica >> ----------------------------------------------------------------- >> Todos somos muy ignorantes, lo que ocurre es que no todos ignoramos lo >> mismo. >> >> Recuerda: El arca de Noe fue construida por aficionados, el titanic >> por profesionales >> ----------------------------------------------------------------- >> _______________________________________________ >> PyQt mailing list [email protected] >> http://www.riverbankcomputing.com/mailman/listinfo/pyqt > -- Lic. José M. Rodriguez Bacallao Centro de Biofisica Medica ----------------------------------------------------------------- Todos somos muy ignorantes, lo que ocurre es que no todos ignoramos lo mismo. Recuerda: El arca de Noe fue construida por aficionados, el titanic por profesionales ----------------------------------------------------------------- _______________________________________________ PyQt mailing list [email protected] http://www.riverbankcomputing.com/mailman/listinfo/pyqt
