如何使用 Qthread 通过 PyQt 更新 Matplotlib 图？
How to use a Qthread to update a Matplotlib figure with PyQt?
我真的很难理解如何在 PyQt 中使用线程。我在 UI 中做了一个我想做的简单例子。在您可以在下面看到的代码中，我希望用户输入一个股票代码（例如，您可以输入 "bby"、"goog" 或 "v"）并将股票的价值绘制在某时段。事情变得更复杂 Ui 或者很长一段时间 UI 在更新情节时冻结。所以我做了一个 "Plotter" class ，当它收到某个信号时更新情节（覆盖 Qthread.run 显然不是正确的方式 you're doing it wrong）。我想在主线程之外的另一个线程中制作此 "Plotter" 运行。
一旦我取消对线程行的注释，程序就会停止工作。我试图移动新线程和 "connect" 的启动，但没有任何效果。我认为即使阅读了 documentation 并查看了 Qt 网站上的示例，我也不太了解 Qthread 的工作原理。
如果您知道如何执行此操作，那将大有帮助！ （我正在使用 Python 3.5 和 PyQt5）
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from matplotlib.axes._subplots import Axes
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
import sys
from datetime import datetime, timedelta
import time
import quandl
class MyMplCanvas(FigureCanvas):
"""Ultimately, this is a QWidget (as well as a FigureCanvasAgg, etc.)."""
send_fig = pyqtSignal(Axes, str, name="send_fig")
def __init__(self, parent=None):
self.fig = Figure()
self.axes = self.fig.add_subplot(111)
# We want the axes cleared every time plot() is called
self.axes.hold(False)
FigureCanvas.__init__(self, self.fig)
self.setParent(parent)
FigureCanvas.setSizePolicy(self, QSizePolicy.Expanding, QSizePolicy.Expanding)
FigureCanvas.updateGeometry(self)
def update_plot(self, axes):
self.axes = axes
self.draw()
class MainWindow(QMainWindow):
send_fig = pyqtSignal(Axes, str, name="send_fig")
def __init__(self):
super().__init__()
self.main_widget = QWidget(self)
self.myplot = MyMplCanvas(self.main_widget)
self.editor = QLineEdit()
self.display = QLabel("Vide")
self.layout = QGridLayout(self.main_widget)
self.layout.addWidget(self.editor)
self.layout.addWidget(self.display)
self.layout.addWidget(self.myplot)
self.main_widget.setFocus()
self.setCentralWidget(self.main_widget)
self.move(500, 500)
self.show()
self.editor.returnPressed.connect(self.updatePlot)
self.plotter = Plotter()
self.send_fig.connect(self.plotter.replot)
self.plotter.return_fig.connect(self.myplot.update_plot)
def updatePlot(self):
ticker = self.editor.text()
self.editor.clear()
self.display.setText(ticker)
# thread = QThread()
# self.plotter.moveToThread(thread)
self.send_fig.emit(self.myplot.axes, ticker)
# thread.start()
class Plotter(QObject):
return_fig = pyqtSignal(Axes)
@pyqtSlot(Axes, str)
def replot(self, axes, ticker): # A slot takes no params
print(ticker)
d = datetime.today() - timedelta(weeks=52) # data from 1week ago
data = quandl.get("YAHOO/"+ticker+".6", start_date=d.strftime("%d-%m-%Y"), end_date=time.strftime("%d-%m-%Y"))
axes.plot(data)
self.return_fig.emit(axes)
if __name__ == '__main__':
app = QApplication(sys.argv)
win = MainWindow()
sys.exit(app.exec_())
第一个问题是一旦启动就失去了对 thread 的引用。要保留引用，请使用 class 变量，即 self.thread 而不是 thread.
接下来，必须在执行任何操作之前启动线程。所以需要在信号发射前加上self.thread.start()
现在，它已经可以工作了，但是一旦您想启动一个新线程，就会出现下一个问题。因此，您需要先杀死旧的。由于旧的 Plotter 将无家可归，因此解决方案是每次要绘制时创建一个新的 Plotter 以及一个新的线程。这就是下面解决方案的工作方式。
或者，您也可以始终使用相同的绘图仪和线程。唯一要记住的是，永远只有一个worker（plotter）和一个thread，如果你删除了其中一个，另一个就很难过了。
为了测试它，我需要改变一些小东西，比如使用 PyQt4 而不是 5 并替换数据生成。
这是工作代码。
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from matplotlib.axes._subplots import Axes
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
import sys
from datetime import datetime, timedelta
import numpy as np
class MyMplCanvas(FigureCanvas):
"""Ultimately, this is a QWidget (as well as a FigureCanvasAgg, etc.)."""
send_fig = pyqtSignal(Axes, str, name="send_fig")
def __init__(self, parent=None):
self.fig = Figure()
self.axes = self.fig.add_subplot(111)
# We want the axes cleared every time plot() is called
self.axes.hold(False)
FigureCanvas.__init__(self, self.fig)
self.setParent(parent)
FigureCanvas.setSizePolicy(self, QSizePolicy.Expanding, QSizePolicy.Expanding)
FigureCanvas.updateGeometry(self)
def update_plot(self, axes):
self.axes = axes
self.draw()
class MainWindow(QMainWindow):
send_fig = pyqtSignal(Axes, str, name="send_fig")
def __init__(self):
super(MainWindow, self).__init__()
self.main_widget = QWidget(self)
self.myplot = MyMplCanvas(self.main_widget)
self.editor = QLineEdit()
self.display = QLabel("Vide")
self.layout = QGridLayout(self.main_widget)
self.layout.addWidget(self.editor)
self.layout.addWidget(self.display)
self.layout.addWidget(self.myplot)
self.main_widget.setFocus()
self.setCentralWidget(self.main_widget)
self.move(500, 500)
self.show()
self.editor.returnPressed.connect(self.updatePlot)
# plotter and thread are none at the beginning
self.plotter = None
self.thread = None
def updatePlot(self):
ticker = self.editor.text()
self.editor.clear()
self.display.setText(ticker)
# if there is already a thread running, kill it first
if self.thread != None and self.thread.isRunning():
self.thread.terminate()
# initialize plotter and thread
# since each plotter needs its own thread
self.plotter = Plotter()
self.thread = QThread()
# connect signals
self.send_fig.connect(self.plotter.replot)
self.plotter.return_fig.connect(self.myplot.update_plot)
#move to thread and start
self.plotter.moveToThread(self.thread)
self.thread.start()
# start the plotting
self.send_fig.emit(self.myplot.axes, ticker)
class Plotter(QObject):
return_fig = pyqtSignal(Axes)
@pyqtSlot(Axes, str)
def replot(self, axes, ticker): # A slot takes no params
print(ticker)
d = datetime.today() - timedelta(weeks=52) # data from 1week ago
# do some random task
data = np.random.rand(10000,10000)
axes.plot(data.mean(axis=1))
self.return_fig.emit(axes)
if __name__ == '__main__':
app = QApplication(sys.argv)
win = MainWindow()
sys.exit(app.exec_())
这里是提到的第二个选项的解决方案，即创建一个工作线程和一个线程，并在整个程序运行时使用它们。
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
import sys
import numpy as np
class MyMplCanvas(FigureCanvas):
def __init__(self, parent=None):
self.fig = Figure()
self.axes = self.fig.add_subplot(111)
# plot empty line
self.line, = self.axes.plot([],[], color="orange")
FigureCanvas.__init__(self, self.fig)
self.setParent(parent)
FigureCanvas.setSizePolicy(self, QSizePolicy.Expanding, QSizePolicy.Expanding)
FigureCanvas.updateGeometry(self)
class MainWindow(QMainWindow):
send_fig = pyqtSignal(str)
def __init__(self):
super(MainWindow, self).__init__()
self.main_widget = QWidget(self)
self.myplot = MyMplCanvas(self.main_widget)
self.editor = QLineEdit()
self.display = QLabel("Vide")
self.layout = QGridLayout(self.main_widget)
self.layout.addWidget(self.editor)
self.layout.addWidget(self.display)
self.layout.addWidget(self.myplot)
self.main_widget.setFocus()
self.setCentralWidget(self.main_widget)
self.show()
# plotter and thread are none at the beginning
self.plotter = Plotter()
self.thread = QThread()
# connect signals
self.editor.returnPressed.connect(self.start_update)
self.send_fig.connect(self.plotter.replot)
self.plotter.return_fig.connect(self.plot)
#move to thread and start
self.plotter.moveToThread(self.thread)
self.thread.start()
def start_update(self):
ticker = self.editor.text()
self.editor.clear()
self.display.setText(ticker)
# start the plotting
self.send_fig.emit(ticker)
# Slot receives data and plots it
def plot(self, data):
# plot data
self.myplot.line.set_data([np.arange(len(data)), data])
# adjust axes
self.myplot.axes.set_xlim([0,len(data) ])
self.myplot.axes.set_ylim([ data.min(),data.max() ])
self.myplot.draw()
class Plotter(QObject):
return_fig = pyqtSignal(object)
@pyqtSlot(str)
def replot(self, ticker):
print(ticker)
# do some random task
data = np.random.rand(10000,10000)
data = data.mean(axis=1)
self.return_fig.emit(data)
if __name__ == '__main__':
app = QApplication(sys.argv)
win = MainWindow()
sys.exit(app.exec_())
我真的很难理解如何在 PyQt 中使用线程。我在 UI 中做了一个我想做的简单例子。在您可以在下面看到的代码中，我希望用户输入一个股票代码（例如，您可以输入 "bby"、"goog" 或 "v"）并将股票的价值绘制在某时段。事情变得更复杂 Ui 或者很长一段时间 UI 在更新情节时冻结。所以我做了一个 "Plotter" class ，当它收到某个信号时更新情节（覆盖 Qthread.run 显然不是正确的方式 you're doing it wrong）。我想在主线程之外的另一个线程中制作此 "Plotter" 运行。
一旦我取消对线程行的注释，程序就会停止工作。我试图移动新线程和 "connect" 的启动，但没有任何效果。我认为即使阅读了 documentation 并查看了 Qt 网站上的示例，我也不太了解 Qthread 的工作原理。
如果您知道如何执行此操作，那将大有帮助！ （我正在使用 Python 3.5 和 PyQt5）
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from matplotlib.axes._subplots import Axes
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
import sys
from datetime import datetime, timedelta
import time
import quandl
class MyMplCanvas(FigureCanvas):
"""Ultimately, this is a QWidget (as well as a FigureCanvasAgg, etc.)."""
send_fig = pyqtSignal(Axes, str, name="send_fig")
def __init__(self, parent=None):
self.fig = Figure()
self.axes = self.fig.add_subplot(111)
# We want the axes cleared every time plot() is called
self.axes.hold(False)
FigureCanvas.__init__(self, self.fig)
self.setParent(parent)
FigureCanvas.setSizePolicy(self, QSizePolicy.Expanding, QSizePolicy.Expanding)
FigureCanvas.updateGeometry(self)
def update_plot(self, axes):
self.axes = axes
self.draw()
class MainWindow(QMainWindow):
send_fig = pyqtSignal(Axes, str, name="send_fig")
def __init__(self):
super().__init__()
self.main_widget = QWidget(self)
self.myplot = MyMplCanvas(self.main_widget)
self.editor = QLineEdit()
self.display = QLabel("Vide")
self.layout = QGridLayout(self.main_widget)
self.layout.addWidget(self.editor)
self.layout.addWidget(self.display)
self.layout.addWidget(self.myplot)
self.main_widget.setFocus()
self.setCentralWidget(self.main_widget)
self.move(500, 500)
self.show()
self.editor.returnPressed.connect(self.updatePlot)
self.plotter = Plotter()
self.send_fig.connect(self.plotter.replot)
self.plotter.return_fig.connect(self.myplot.update_plot)
def updatePlot(self):
ticker = self.editor.text()
self.editor.clear()
self.display.setText(ticker)
# thread = QThread()
# self.plotter.moveToThread(thread)
self.send_fig.emit(self.myplot.axes, ticker)
# thread.start()
class Plotter(QObject):
return_fig = pyqtSignal(Axes)
@pyqtSlot(Axes, str)
def replot(self, axes, ticker): # A slot takes no params
print(ticker)
d = datetime.today() - timedelta(weeks=52) # data from 1week ago
data = quandl.get("YAHOO/"+ticker+".6", start_date=d.strftime("%d-%m-%Y"), end_date=time.strftime("%d-%m-%Y"))
axes.plot(data)
self.return_fig.emit(axes)
if __name__ == '__main__':
app = QApplication(sys.argv)
win = MainWindow()
sys.exit(app.exec_())
第一个问题是一旦启动就失去了对 thread 的引用。要保留引用，请使用 class 变量，即 self.thread 而不是 thread.
接下来，必须在执行任何操作之前启动线程。所以需要在信号发射前加上self.thread.start()
现在，它已经可以工作了，但是一旦您想启动一个新线程，就会出现下一个问题。因此，您需要先杀死旧的。由于旧的 Plotter 将无家可归，因此解决方案是每次要绘制时创建一个新的 Plotter 以及一个新的线程。这就是下面解决方案的工作方式。
或者，您也可以始终使用相同的绘图仪和线程。唯一要记住的是，永远只有一个worker（plotter）和一个thread，如果你删除了其中一个，另一个就很难过了。
为了测试它，我需要改变一些小东西，比如使用 PyQt4 而不是 5 并替换数据生成。 这是工作代码。
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from matplotlib.axes._subplots import Axes
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
import sys
from datetime import datetime, timedelta
import numpy as np
class MyMplCanvas(FigureCanvas):
"""Ultimately, this is a QWidget (as well as a FigureCanvasAgg, etc.)."""
send_fig = pyqtSignal(Axes, str, name="send_fig")
def __init__(self, parent=None):
self.fig = Figure()
self.axes = self.fig.add_subplot(111)
# We want the axes cleared every time plot() is called
self.axes.hold(False)
FigureCanvas.__init__(self, self.fig)
self.setParent(parent)
FigureCanvas.setSizePolicy(self, QSizePolicy.Expanding, QSizePolicy.Expanding)
FigureCanvas.updateGeometry(self)
def update_plot(self, axes):
self.axes = axes
self.draw()
class MainWindow(QMainWindow):
send_fig = pyqtSignal(Axes, str, name="send_fig")
def __init__(self):
super(MainWindow, self).__init__()
self.main_widget = QWidget(self)
self.myplot = MyMplCanvas(self.main_widget)
self.editor = QLineEdit()
self.display = QLabel("Vide")
self.layout = QGridLayout(self.main_widget)
self.layout.addWidget(self.editor)
self.layout.addWidget(self.display)
self.layout.addWidget(self.myplot)
self.main_widget.setFocus()
self.setCentralWidget(self.main_widget)
self.move(500, 500)
self.show()
self.editor.returnPressed.connect(self.updatePlot)
# plotter and thread are none at the beginning
self.plotter = None
self.thread = None
def updatePlot(self):
ticker = self.editor.text()
self.editor.clear()
self.display.setText(ticker)
# if there is already a thread running, kill it first
if self.thread != None and self.thread.isRunning():
self.thread.terminate()
# initialize plotter and thread
# since each plotter needs its own thread
self.plotter = Plotter()
self.thread = QThread()
# connect signals
self.send_fig.connect(self.plotter.replot)
self.plotter.return_fig.connect(self.myplot.update_plot)
#move to thread and start
self.plotter.moveToThread(self.thread)
self.thread.start()
# start the plotting
self.send_fig.emit(self.myplot.axes, ticker)
class Plotter(QObject):
return_fig = pyqtSignal(Axes)
@pyqtSlot(Axes, str)
def replot(self, axes, ticker): # A slot takes no params
print(ticker)
d = datetime.today() - timedelta(weeks=52) # data from 1week ago
# do some random task
data = np.random.rand(10000,10000)
axes.plot(data.mean(axis=1))
self.return_fig.emit(axes)
if __name__ == '__main__':
app = QApplication(sys.argv)
win = MainWindow()
sys.exit(app.exec_())
这里是提到的第二个选项的解决方案，即创建一个工作线程和一个线程，并在整个程序运行时使用它们。
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
import sys
import numpy as np
class MyMplCanvas(FigureCanvas):
def __init__(self, parent=None):
self.fig = Figure()
self.axes = self.fig.add_subplot(111)
# plot empty line
self.line, = self.axes.plot([],[], color="orange")
FigureCanvas.__init__(self, self.fig)
self.setParent(parent)
FigureCanvas.setSizePolicy(self, QSizePolicy.Expanding, QSizePolicy.Expanding)
FigureCanvas.updateGeometry(self)
class MainWindow(QMainWindow):
send_fig = pyqtSignal(str)
def __init__(self):
super(MainWindow, self).__init__()
self.main_widget = QWidget(self)
self.myplot = MyMplCanvas(self.main_widget)
self.editor = QLineEdit()
self.display = QLabel("Vide")
self.layout = QGridLayout(self.main_widget)
self.layout.addWidget(self.editor)
self.layout.addWidget(self.display)
self.layout.addWidget(self.myplot)
self.main_widget.setFocus()
self.setCentralWidget(self.main_widget)
self.show()
# plotter and thread are none at the beginning
self.plotter = Plotter()
self.thread = QThread()
# connect signals
self.editor.returnPressed.connect(self.start_update)
self.send_fig.connect(self.plotter.replot)
self.plotter.return_fig.connect(self.plot)
#move to thread and start
self.plotter.moveToThread(self.thread)
self.thread.start()
def start_update(self):
ticker = self.editor.text()
self.editor.clear()
self.display.setText(ticker)
# start the plotting
self.send_fig.emit(ticker)
# Slot receives data and plots it
def plot(self, data):
# plot data
self.myplot.line.set_data([np.arange(len(data)), data])
# adjust axes
self.myplot.axes.set_xlim([0,len(data) ])
self.myplot.axes.set_ylim([ data.min(),data.max() ])
self.myplot.draw()
class Plotter(QObject):
return_fig = pyqtSignal(object)
@pyqtSlot(str)
def replot(self, ticker):
print(ticker)
# do some random task
data = np.random.rand(10000,10000)
data = data.mean(axis=1)
self.return_fig.emit(data)
if __name__ == '__main__':
app = QApplication(sys.argv)
win = MainWindow()
sys.exit(app.exec_())