python - 动态更新 QChart

Question

我有一个为给定数据绘制烛台的类(class)。我正在尝试在收到新数据后立即动态更新绘图。以不规则的间隔接收数据。
我可以使用什么机制让类(class)知道是时候更新绘图并根据新接收的数据点更新绘图？
类函数append_data_and_plot()追加数据，但情节永远不会更新。有人可以解释一下这个问题是什么吗？

import sys
from PyQt5.QtChart import QCandlestickSeries, QChart, QChartView, QCandlestickSet
from PyQt5.QtWidgets import QApplication, QMainWindow
from PyQt5.QtCore import Qt, QPointF
from PyQt5 import QtChart as qc
import time

class myCandlestick():
    def __init__(self, data):
        self.data = data
        self.app = QApplication(sys.argv)

        self.series = QCandlestickSeries()
        self.series.setDecreasingColor(Qt.red)
        self.series.setIncreasingColor(Qt.green)

        self.ma5 = qc.QLineSeries() 
        self.tm = []

        for num, o, h, l, c, m in self.data:
            self.series.append(QCandlestickSet(o, h, l, c))
            self.ma5.append(QPointF(num, m))
            self.tm.append(str(num))

        self.chart = QChart()

        self.chart.addSeries(self.series)  # candle
        self.chart.addSeries(self.ma5)  # ma5 line

        self.chart.createDefaultAxes()
        self.chart.legend().hide()

        self.chart.axisX(self.series).setCategories(self.tm)
        self.chart.axisX(self.ma5).setVisible(False)

        self.chartview = QChartView(self.chart)
        self.ui = QMainWindow()
        self.ui.setGeometry(50, 50, 500, 300)
        self.ui.setCentralWidget(self.chartview)
        self.ui.show()
        sys.exit(self.app.exec_())

    def append_data_and_plot(self, d):
        '''Append and update the plot'''
        num, o, h, l, c, m = d
        self.series.append(QCandlestickSet(o, h, l, c))
        self.ui.show()
        #sys.exit(self.app.exec_())


data = ((1, 7380, 7520, 7380, 7510, 7324),
        (2, 7520, 7580, 7410, 7440, 7372),
        (3, 7440, 7650, 7310, 7520, 7434),
        (4, 7450, 7640, 7450, 7550, 7480),
        (5, 7510, 7590, 7460, 7490, 7502),
        (6, 7500, 7590, 7480, 7560, 7512),
        (7, 7560, 7830, 7540, 7800, 7584))

m = myCandlestick(data)

# Data is received at irregular intervals
time.sleep(1)
m.append_data_and_plot((8, 7560, 7830, 7540, 7800, 7584))

# Data is received at irregular intervals
time.sleep(0.1)
m.append_data_and_plot((9, 7450, 7640, 7450, 7550, 7480))

# Data is received at irregular intervals
time.sleep(2.5)
m.append_data_and_plot((10, 7380, 7520, 7380, 7510, 7324))

Answer 1

Qt 使用事件循环来处理 gui 的事件和任务，即代码“app.exec_()”，因此该行之后的所有代码都不会被执行，如果添加到该代码中则使用 sys .exit() 将使应用程序在 Qt 事件循环结束时终止。
解决方案是使用 eventloop 来更新 gui，例如使用 QTimer:

import sys
from PyQt5.QtChart import QCandlestickSeries, QChart, QChartView, QCandlestickSet
from PyQt5.QtWidgets import QApplication, QMainWindow
from PyQt5.QtCore import Qt, QPointF, QObject, pyqtSignal, QTimer
from PyQt5 import QtChart as qc

import random


class MainWindow(QMainWindow):
    def __init__(self, data, parent=None):
        super().__init__(parent)
        self.data = data

        self.series = QCandlestickSeries()
        self.series.setDecreasingColor(Qt.red)
        self.series.setIncreasingColor(Qt.green)

        self.ma5 = qc.QLineSeries()
        self.tm = []

        self.chart = QChart()

        self.chart.addSeries(self.series)  # candle
        self.chart.addSeries(self.ma5)  # ma5 line

        self.chart.createDefaultAxes()
        self.chart.legend().hide()

        self.chart.axisX(self.series).setCategories(self.tm)
        self.chart.axisX(self.ma5).setVisible(False)

        self.chartview = QChartView(self.chart)
        self.setGeometry(50, 50, 500, 300)
        self.setCentralWidget(self.chartview)

    def append_data_and_plot(self, d):
        """Append and update the plot"""
        num, o, h, l, c, m = d

        ax1 = self.chart.axisX(self.ma5)
        ay1 = self.chart.axisY(self.ma5)

        xmin = xmax = num
        ymin = ymax = m

        step = 10
        offset = 100

        for p in self.ma5.pointsVector()[-step:]:
            xmin = min(p.x(), xmin)
            xmax = max(p.x(), xmax)

            ymin = min(p.y(), ymin) - offset
            ymax = max(p.y(), ymax) + offset

        xmin = max(0, xmax - step)

        ax1.setMin(xmin)
        ax1.setMax(xmax)
        ay1.setMin(ymin)
        ay1.setMax(ymax)

        self.ma5.append(QPointF(num, m))
        self.tm.append(str(num))

        self.series.append(QCandlestickSet(o, h, l, c))
        ax2 = self.chart.axisX(self.series)
        ax2.setCategories(self.tm)
        ax2.setMin(str(xmin))
        ax2.setMax(str(xmax))

        ay2 = self.chart.axisY(self.series)
        ay2.setMin(ymin)
        ay2.setMax(ymax)


def create_data():


    i = 1
    while True:
        i += 1
        yield (
            i,
            random.randint(7000, 8000),
            random.randint(7000, 8000),
            random.randint(7000, 8000),
            random.randint(7000, 8000),
            random.randint(7000, 8000),
        )


class Producer(QObject):
    dataChanged = pyqtSignal(list)

    def __init__(self, parent=None):
        super().__init__(parent)
        self.iter = create_data()
        QTimer.singleShot(random.randint(0, 1500), self.send_data)

    def send_data(self):
        d = list(next(self.iter))
        self.dataChanged.emit(d)
        QTimer.singleShot(random.randint(0, 1500), self.send_data)


def main():
    app = QApplication(sys.argv)

    data = ((1, 7380, 7520, 7380, 7510, 7324),)
    w = MainWindow(data)
    w.show()

    p = Producer()
    p.dataChanged.connect(w.append_data_and_plot)

    sys.exit(app.exec_())


if __name__ == "__main__":
    main()