如何阻止matplotlib GUI线程冻结

Question

from matplotlib import pyplot as p
from scipy import zeros
from Queue import Queue
import random
w,h = 320,200
black = zeros((h,w,3), dtype='uint8')
red = black.copy(); red[:,:,0] = 255
green = black.copy(); green[:,:,1] = 255
blue = black.copy(); blue[:,:,2] = 255
def ants():
  from scipy import rand, dstack
  return dstack([(255*rand(h,w)).astype('uint8')]*3)
fig = p.figure()
axs = [fig.add_subplot(1,3,i) for i in xrange(3)]
[ax.imshow(black) for ax in axs]
q = Queue()
def update_image(ax):
  ## this takes some time
  import time
  time.sleep(3)
  ax.images[0].set_data(random.choice([red, green, blue]))
def hit(event):
  if event.inaxes in axs:
    update_axs = [event.inaxes]
  else:
    update_axs = axs
  for ax in update_axs:
    ax.images[0].set_data(ants())
  p.draw()
#  for ax in update_axs:
#    update_image(ax)
#  p.draw()
cid = fig.canvas.mpl_connect('button_press_event', hit)
p.show()

这是我的代码，这一切工作如预期。但是，当我取消事件处理程序中的这3行注释时，出现了一些我没有预料到的问题。首先，GUI冻结，而update_image正在工作，其次，第一次调用draw()似乎没有机会油漆，因为我没有看到赛车蚂蚁，而update_image正在工作。在matplotlib中设置这种东西以使其顺利工作的更好方法是什么?

Answer 1

为了避免冻结GUI，您需要在单独的线程或进程中运行update_image。使用threading，您可以这样做:

import matplotlib
matplotlib.use('TkAgg')
from matplotlib import pyplot as p
from scipy import zeros
import random
import threading

w,h = 320,200
black = zeros((h,w,3), dtype='uint8')
red = black.copy(); red[:,:,0] = 255
green = black.copy(); green[:,:,1] = 255
blue = black.copy(); blue[:,:,2] = 255
def ants():
    from scipy import rand, dstack
    return dstack([(255*rand(h,w)).astype('uint8')]*3)
fig = p.figure()
axs = [fig.add_subplot(1,3,i) for i in xrange(3)]
[ax.imshow(black) for ax in axs]
def update_image(ax):
    ## this takes some time
    import time
    time.sleep(3)
    ax.images[0].set_data(random.choice([red, green, blue]))
    ax.figure.canvas.draw()
def hit(event):
    if event.inaxes in axs:
        update_axs = [event.inaxes]
    else:
        update_axs = axs
    for ax in update_axs:
        ax.images[0].set_data(ants())
    p.draw()
    for ax in update_axs:
        t=threading.Thread(target=update_image,args=(ax,))
        t.daemon=True
        t.start()
cid = fig.canvas.mpl_connect('button_press_event', hit)
p.show()