Dear all,
I have recently started to try plplot to plot realtime data. I have
extensively used matplotlib but found it for realtime much to slow. So I
tried plplot and I got pretty fast nice results using plplot.
I have anyhow a segfault problem with my python code and I do not fully
understand why.
What I experienced when e.g. applying the examples is that a resizing of
the window does resizes the axes only when the window is resized
according to the axes aspect ratio. So a resizing of the window in e.g.
only the x-direction does not resize the plplot axes.
What I found to work is that after a window resize you cleanup your
existing plplot widgets ( calling plend(), plfreeqtdev() ) and start all
over. This works quite well, but I get random segfaults. Attached is my
python code, it should work out of the box.
Any help is appreciated!
Cheers,
Peter
# ------------------Snip-----------------------
import sys
import numpy as np
import plplot
# An indirect side effect of this import statement is a consistent set
# of Qt4 libraries are loaded (e.g., if those are from some downloaded
# non-system version in a non-standard location).
import plplot_pyqt4
# This import statement must go after the one above to insure a
# consistent set of Qt4 libraries are used for the case of the
# downloaded, non-standard location of those libraries.
from PyQt4 import QtCore, QtGui
class plplot_Widget_test2(QtGui.QWidget):
"""
A plplot canvas widget
"""
def __init__(self,parent=None,numstream=0,pause=1,nsub=1):
QtGui.QWidget.__init__(self)
self.setParent(parent)
self.nsub = nsub
self.x_data = []
self.y_data = []
self.x_all = []
self.y_all = []
self.init = True
def plplotInit(self):
if(self.init):
width = 200
height = 200
self.init = False
else:
width = self.frameSize().width()
height = self.frameSize().height()
print "Init",width,height
# PLplot setup
self.plot = plplot_pyqt4.QtExtWidget(width, height, self)
plplot_pyqt4.plsetqtdev(self.plot)
plplot.plsdev("extqt")
plplot.plinit()
self.plplotinitAxes()
print "End plotinitaxes"
def plplotstartTimer(self):
print "Timer"
self.timer = QtCore.QTimer(self)
self.timer.timeout.connect(self.plplotupdatePlot)
self.timer.start(200)
print "Timer end"
def plplotinitAxes(self):
print "initAxes"
colbox = 1
collab = 3
styline = [2, 3, 4, 5]
colline = [2, 3, 4, 5]
legline = ["1", "2", "3", "4"]
xlab = 0.
ylab = 0.25 # legend position
autoy = 1 # autoscale y
acc = 1 # don t scrip, accumulate
self.id = []
# Register our error variables with PLplot
# From here on, we're handling all errors here
if(self.nsub>1):
plplot.plssub(2, 2)
for i in range(self.nsub):
plplot.pladv(0)
plplot.plvsta()
tmin = 0
tmax = 10
tjump = .3
ymin = -.10
ymax = .10
print "New Axes!"
id = plplot.plstripc("bcnst", "bcnstv",
tmin, tmax, tjump, ymin, ymax,
xlab, ylab,
autoy, acc,
colbox, collab,
colline, styline, legline,
"Hello!", "", "Strip chart demo")
self.id.append(id)
print "End New Axes!"
self.update()
def plplotupdatePlot(self):
if(len(self.x_data)>0):
print "Update plot 1",self.x_data
while(len(self.x_data)>0):
x = self.x_data.pop(0)
y = self.y_data.pop(0)
self.x_all.append(x)
self.y_all.append(y)
for i in range(self.nsub):
plplot.pladv(i+1)
plplot.plstripa(self.id[i], 0, x, y)
self.update()
def plplotCleanup(self):
print "Cleanup"
self.timer.stop()
plplot.plend()
plplot_pyqt4.plfreeqtdev()
print "End Cleanup"
def resizeEvent(self, event):
self.plplotCleanup()
self.plplotInit()
self.plplotstartTimer()
class QPlot(QtGui.QMainWindow):
def __init__(self):
QtGui.QMainWindow.__init__(self, None)
self.resize(300,300)
self.lw = QtGui.QWidget(self)
self.l = QtGui.QVBoxLayout(self.lw)
self.lw1 = plplot_Widget_test2(self,nsub=4)
self.l.addWidget(self.lw1)
self.lw1.plplotInit()
self.lw1.plplotstartTimer()
self.setCentralWidget(self.lw)
print "Init random data generator"
timer = QtCore.QTimer(self)
timer.timeout.connect(self.data_gen)
timer.start(250)
self.n = 0
def data_gen(self):
self.n += 1
self.lw1.x_data.append(self.n * 0.1)
self.lw1.y_data.append(np.random.rand(1)[0])
app = QtGui.QApplication(sys.argv)
plot = QPlot()
plot.show()
app.exec_()
plot.lw1.plplotCleanup()
------------------------------------------------------------------------------
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