pyqtgraph 中的动画图表

Question

我正在使用 pyqtchart 进行第一次测试，但由于有关动画图表的文档不多，我遇到了一些问题。我构建了一个图表来显示 'sin'、'cos' 和 'tan' 函数（近似切线值）并使其生效我构建了一个线程来清除并重新绘制图表每次。它有效，但我不知道这是正确的方法还是最有效的方法。我在 github 上找到了一个示例，但我不太清楚。

我不明白这是 'offical way' 做的，还是 pyqtgraph 提供了一些内置函数来自动化它。如果有人能给我一些建议，我将非常感激。

这是我的代码：

from PyQt5.QtWidgets import *
from PyQt5.QtCore import QThread, pyqtSignal
import pyqtgraph as pg
import math
import numpy as np
import sys
import time

class Gui(QWidget):
    def __init__(self):
        super().__init__()
        self.setupUI()

    def setupUI(self):
        pg.setConfigOption('background', 0.95)
        pg.setConfigOptions(antialias=True)
        self.plot = pg.PlotWidget()
        self.plot.setAspectLocked(lock=True, ratio=0.01)
        self.plot.setYRange(-3, 3)
        self.widget_layout = QVBoxLayout()
        self.widget_layout.addWidget(self.plot)
        self.setLayout(self.widget_layout)

    def plot_data(self, data):
        self.plot.clear()
        self.plot.plot(range(0, 720), data[0], pen=pg.mkPen(color='g', width=2))
        self.plot.plot(range(0, 720), data[1], pen=pg.mkPen(color='r', width=2))
        self.plot.plot(range(0, 720), data[2], pen=pg.mkPen(color='y', width=2))

class Thread(QThread):
    sig_plot = pyqtSignal(list)
    def __init__(self):
        super().__init__()
        self.sig_plot.connect(gui.plot_data)

    def run(self):
        sin_func = np.empty(720)
        cos_func = np.empty(720)
        tan_func = np.empty(720)
        cont = 0
        while True:
            indx = 0
            for ang in range(cont, cont + 720):
                rad = math.radians(ang)
                cos = math.cos(rad)
                sin = math.sin(rad)
                if cos != 0: tan = sin / cos
                else: tan = sin / 0.00000000001
                sin_func[indx] = sin
                cos_func[indx] = cos
                if tan >= -3 and tan <= 3: tan_func[indx] = tan
                else: tan_func[indx] = np.NaN
                indx += 1
            data = [sin_func, cos_func, tan_func]
            self.sig_plot.emit(data)
            time.sleep(0.01)
            if cont == 720: cont = 0
            else: cont += 1

if __name__ == '__main__':
    app = QApplication(sys.argv)
    gui = Gui()
    gui.show()
    thread = Thread()
    thread.start()
    sys.exit(app.exec_())

Answer 1

在 pyqtgraph 中没有制作动画的官方方法，但你采样的方法不是最好的，因为 GUI 中的线程只有在任务繁重时才需要，但创建数组的任务不是，另一个错误是清理和创建地块，在这些情况下最好重新使用。最后在矩阵和数组层面利用numpy的计算能力比做循环更好

考虑到上述情况，我已经实现了一个 class，它每隔一定时间间隔使用适当的索引调用函数 generate_data，并在 QTimer 的帮助下生成一个无限循环。

from PyQt5 import QtCore, QtWidgets
import pyqtgraph as pg
import numpy as np

class TimeLine(QtCore.QObject):
    frameChanged = QtCore.pyqtSignal(int)

    def __init__(self, interval=60, loopCount=1, parent=None):
        super(TimeLine, self).__init__(parent)
        self._startFrame = 0
        self._endFrame = 0
        self._loopCount = loopCount
        self._timer = QtCore.QTimer(self, timeout=self.on_timeout)
        self._counter = 0
        self._loop_counter = 0
        self.setInterval(interval)

    def on_timeout(self):
        if self._startFrame <= self._counter < self._endFrame:
            self.frameChanged.emit(self._counter)
            self._counter += 1
        else:
            self._counter = 0
            self._loop_counter += 1

        if self._loopCount > 0: 
            if self._loop_counter >= self.loopCount():
                self._timer.stop() 

    def setLoopCount(self, loopCount):
        self._loopCount = loopCount

    def loopCount(self):
        return self._loopCount

    interval = QtCore.pyqtProperty(int, fget=loopCount, fset=setLoopCount)

    def setInterval(self, interval):
        self._timer.setInterval(interval)

    def interval(self):
        return self._timer.interval()

    interval = QtCore.pyqtProperty(int, fget=interval, fset=setInterval)

    def setFrameRange(self, startFrame, endFrame):
        self._startFrame = startFrame
        self._endFrame = endFrame

    @QtCore.pyqtSlot()
    def start(self):
        self._counter = 0
        self._loop_counter = 0
        self._timer.start()


class Gui(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()
        self.setupUI()

    def setupUI(self):
        pg.setConfigOption('background', 0.95)
        pg.setConfigOptions(antialias=True)
        self.plot = pg.PlotWidget()
        self.plot.setAspectLocked(lock=True, ratio=0.01)
        self.plot.setYRange(-3, 3)
        widget_layout = QtWidgets.QVBoxLayout(self)
        widget_layout.addWidget(self.plot)

        self._plots = [self.plot.plot([], [], pen=pg.mkPen(color=color, width=2)) for color in ("g", "r", "y")]
        self._timeline = TimeLine(loopCount=0, interval=10)
        self._timeline.setFrameRange(0, 720)
        self._timeline.frameChanged.connect(self.generate_data)
        self._timeline.start()

    def plot_data(self, data):
        for plt, val in zip(self._plots, data):
            plt.setData(range(len(val)), val)

    @QtCore.pyqtSlot(int)
    def generate_data(self, i):
        ang = np.arange(i, i + 720)
        cos_func = np.cos(np.radians(ang)) 
        sin_func = np.sin(np.radians(ang))
        tan_func = sin_func/cos_func
        tan_func[(tan_func < -3) | (tan_func > 3)] = np.NaN
        self.plot_data([sin_func, cos_func, tan_func])

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    gui = Gui()
    gui.show()
    sys.exit(app.exec_())

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