I'm trying to plot live the output of a generator.
The following code works as expected (Ctrl-C terminates execution):
import numpy as np
import pylab as p
from Queue import Queue
from threading import Thread
import time
def dataGenerator():
while True:
yield np.random.random()
def populate():
f = dataGenerator()
while True:
x = f.next(); y = f.next()
q.put([x,y])
q = Queue()
p.figure(); p.hold(True); p.show(block=False)
populatorThread = Thread(target=populate)
populatorThread.daemon = True
populatorThread.start()
while True:
data = q.get()
x = data[0]
y = data[1]
p.plot(x,y,'o')
p.draw()
q.task_done()
populatorThread.join()
However, if instead I put the plotting in a thread, I get RuntimeError: main thread is not in main loop:
import numpy as np
import pylab as p
from Queue import Queue
from threading import Thread
import time
def dataGenerator():
while True:
yield np.random.random()
def plotter():
while True:
data = q.get()
x = data[0]
y = data[1]
p.plot(x,y,'o')
p.draw()
print x,y
q.task_done()
q = Queue()
p.figure(); p.hold(True); p.show(block=False)
plotThread = Thread(target=plotter)
plotThread.daemon = True
plotThread.start()
f = dataGenerator()
while True:
x = f.next()
y = f.next()
q.put([x,y])
plotThread.join()
Why does matplotlib care which thread does the plotting?
EDIT: I'm not asking how to solve this but rather why is this happening in the first place.
