我知道在matplotlib和线程上有很多问题，而且pyplot也不是线程。然而，我找不到关于这个特定问题的任何内容。我想要做的是：绘制一个数字并每秒更新一次。为此，我想创建一个线程，但到目前为止，我甚至无法从线程中获得真实的情节。此外，我坚持使用qt4，因此可能是其他后端表现不同。
这是一个非常简单的例子：创建了一个情节 plot_a_graph()。从主程序调用时这很好，但是延迟了主代码的进一步执行。但是，从线程调用时，不会显示任何图形。
import matplotlib
matplotlib.use("qt4agg")
import matplotlib.pyplot as plt
import threading
import time
def plot_a_graph():
f,a = plt.subplots(1)
line = plt.plot(range(10))
plt.show()
print "plotted graph"
time.sleep(4)
testthread = threading.Thread(target=plot_a_graph)
plot_a_graph() # this works fine, displays the graph and waits
print "that took some time"
testthread.start() # Thread starts, window is opened but no graph appears
print "already there"
谢谢你的帮助
我的建议是使用python 多 模块而不是线程模块。我已经能够对您的示例代码执行稍微修改，并成功地将matplotlib绘图卸载到子进程，同时主进程中的控制流继续（请参阅下面的代码）。
如果您希望子进程在较大的代码控制流（不是'上下文中）与父进程来回通信，我建议您阅读多处理文档或有关该主题的任何过多博客文章。在你的问题中完整描述）。请注意，多处理具有绕过python的附加优势 全球翻译锁 并允许您利用多核计算机体系结构。
#a slight modification of your code using multiprocessing
import matplotlib
matplotlib.use("qt4agg")
import matplotlib.pyplot as plt
#import threading
#let's try using multiprocessing instead of threading module:
import multiprocessing
import time
#we'll keep the same plotting function, except for one change--I'm going to use the multiprocessing module to report the plotting of the graph from the child process (on another core):
def plot_a_graph():
f,a = plt.subplots(1)
line = plt.plot(range(10))
print multiprocessing.current_process().name,"starting plot show process" #print statement preceded by true process name
plt.show() #I think the code in the child will stop here until the graph is closed
print multiprocessing.current_process().name,"plotted graph" #print statement preceded by true process name
time.sleep(4)
#use the multiprocessing module to perform the plotting activity in another process (i.e., on another core):
job_for_another_core = multiprocessing.Process(target=plot_a_graph,args=())
job_for_another_core.start()
#the follow print statement will also be modified to demonstrate that it comes from the parent process, and should happen without substantial delay as another process performs the plotting operation:
print multiprocessing.current_process().name, "The main process is continuing while another process deals with plotting."
使用Qt信号在主线程中调用绘图功能
import matplotlib
matplotlib.use("qt4agg")
import matplotlib.pyplot as plt
import threading
import time
from PyQt4 import QtCore
class Call_in_QT_main_loop(QtCore.QObject):
signal = QtCore.pyqtSignal()
def __init__(self, func):
super().__init__()
self.func = func
self.args = list()
self.kwargs = dict()
self.signal.connect(self._target)
def _target(self):
self.func(*self.args, **self.kwargs)
def __call__(self, *args, **kwargs):
self.args = args
self.kwargs = kwargs
self.signal.emit()
@Call_in_QT_main_loop
def plot_a_graph():
f,a = plt.subplots(1)
line = plt.plot(range(10))
plt.show()
print("plotted graph")
print(threading.current_thread()) # print the thread that runs this code
def worker():
plot_a_graph()
print(threading.current_thread()) # print the thread that runs this code
time.sleep(4)
testthread = threading.Thread(target=worker)
testthread.start()