为什么matplotlib要求仅在主线程中进行绘制? [英] Why matplotlib requires to plot only in the main thread?
问题描述
我正在尝试绘制发电机的输出.
I'm trying to plot live the output of a generator.
以下代码按预期工作(Ctrl-C终止执行):
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()
但是,如果我改为将绘图放置在线程中,则会得到RuntimeError: main thread is not in main loop
:
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()
为什么matplotlib
关心绘制哪个线程?
Why does matplotlib
care which thread does the plotting?
我不是在问如何解决这个问题,而是为什么会首先发生这种情况.
I'm not asking how to solve this but rather why is this happening in the first place.
推荐答案
可能是您用于后端的GUI. GUI可能希望在主线程中找到自己,但不是在matplotlib调用get_current_fig_manager().canvas.draw()
时出现.
It's probably the GUI that you're using for backend. The GUI likely expects to find itself in the main thread, but it isn't when matplotlib calls get_current_fig_manager().canvas.draw()
.
例如,当我这样做时,我得到以下回溯:
For example, when I do this, I get the following traceback:
Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
self.run()
File "/usr/lib/python2.7/threading.py", line 763, in run
self.__target(*self.__args, **self.__kwargs)
File "tmp.py", line 18, in plotter
p.draw()
File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 555, in draw
get_current_fig_manager().canvas.draw()
File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 349, in draw
tkagg.blit(self._tkphoto, self.renderer._renderer, colormode=2)
File "/usr/lib/pymodules/python2.7/matplotlib/backends/tkagg.py", line 13, in blit
tk.call("PyAggImagePhoto", photoimage, id(aggimage), colormode, id(bbox_array))
RuntimeError: main thread is not in main loop
请注意tk.call(...)
行.您获得的异常不是从matplotlib引发的,而是从TkInter引发的.
Note the tk.call(...)
line. The exception you get is not raised from matplotlib, it's raised from TkInter.
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