向PYQT图表添加新值以按需更新图表

Question

我正在尝试在Pyqt5中使用Pyqtgraph制作烛台图，每次调用方法都会使用新数据更新图形。 我命名了DPoint_Var类中的New_dpoint，该方法将每次激活的数组中添加了另一行随机数据，将由烛台类读取。

经过很长时间，我正在刷我的python，我才刚刚开始学习PYQT库并试图理解它。

截至目前，我对此脚本的结果有一个问题。 由于某种原因，当我运行脚本时，我会收到此错误

------------------------------------------------------------------------

---
IndexError                                Traceback (most recent call last)
Input In [5], in <cell line: 99>()
     96 dpoint = dpoint_var()
     97 dpoint.new_dpoint()
---> 99 item = CandlestickItem(dpoint_var.data2)
    100 plt = pg.plot()
    101 plt.addItem(item)

Input In [5], in CandlestickItem.__init__(self, data)
     64 pg.GraphicsObject.__init__(self)
     65 self.data = data  ## data must have fields: time, open, close, min, max
---> 66 self.generatePicture()

Input In [5], in CandlestickItem.generatePicture(self)
     72 p = QtGui.QPainter(self.picture)
     73 p.setPen(pg.mkPen('w'))
---> 74 width = (self.data[1][0] - self.data[0][0]) / 3.
     75 for (t, open, close, min, max) in self.data:
     76     p.drawLine(QtCore.QPointF(t, min), QtCore.QPointF(t, max))

IndexError: index 1 is out of bounds for axis 0 with size 0

，这似乎表明dpoint.new_dpoint方法未被激活，但我不明白为什么不。

另外，我还试图找到一种方法来从外部函数而不是从QTimer函数内部更新PyqtGraph，因为我只希望在从外部源可用的新数据（而不是定期间隔）中刷新数据。 在不重新绘制整个图表的情况下，正确执行此操作的方法是什么？

import pyqtgraph as pg
import numpy as np
from PyQt5 import QtWidgets, QtCore
from pyqtgraph import PlotWidget, plot, QtCore, QtGui
import sys 
import os
from random import randint

class dpoint_var:
    dpoint = 20
    data = np.empty((0,5), dtype = float)
    data2 = np.empty((0,5), dtype = float)
    def __init__(self):
        def return_dpoint():
            return self.dpoint
        

    def new_dpoint(self):
        self.data = np.random.uniform(low=0.0005, high=0.01, size=(self.dpoint,5))
        self.data2 = np.empty((self.dpoint,5), dtype = float)
        #set the first column to an ordered number line
        x = 0
        for i in range(len(self.data[:,0])):
            self.data2[i][0] = x
            x += 1

        #set the second column to the opening data
        for i in range(len(self.data[:,1])):
            if i > 10:        
                self.data2[i][1] = self.data[i-10][1]
            else:
                self.data2[i][1] = self.data[i][1] 


        #set the third column to the closing data
        for i in range(len(self.data[:,2])):
            self.data2[i][2] = self.data[i][1]


        #set the fourth column to the minimum bat value for the time period
        for i in range(len(self.data[:,3])):
            if i > 10:
                self.data2[i][3] = self.data[i-10:i, 1].min()

            else:
                for i in range(len(self.data[:,3])):
                    self.data2[i][3] = self.data[i][3]

        #set the fourth column to the minimum bat value for the time period
        for i in range(len(self.data[:,4])):
            if i > 10:
                self.data2[i][4] = self.data[i-1:i, 1].max()

            else:
                for i in range(len(self.data[:,4])):
                    self.data2[i][4] = self.data[i][4]
        dpoint.dpoint +=1

--------------------------------------------------------------------------------------    

## Create a subclass of GraphicsObject.
## The only required methods are paint() and boundingRect() 
## (see QGraphicsItem documentation)
class CandlestickItem(pg.GraphicsObject):
    def __init__(self, data):
        pg.GraphicsObject.__init__(self)
        self.data = data  ## data must have fields: time, open, close, min, max
        self.generatePicture()
    
    def generatePicture(self):
        ## pre-computing a QPicture object allows paint() to run much more quickly, 
        ## rather than re-drawing the shapes every time.
        self.picture = QtGui.QPicture()
        p = QtGui.QPainter(self.picture)
        p.setPen(pg.mkPen('w'))
        width = (self.data[1][0] - self.data[0][0]) / 3.
        for (t, open, close, min, max) in self.data:
            p.drawLine(QtCore.QPointF(t, min), QtCore.QPointF(t, max))
            if open > close:
                p.setBrush(pg.mkBrush('r'))
            else:
                p.setBrush(pg.mkBrush('g'))
            p.drawRect(QtCore.QRectF(t-width, open, width*2, close-open))
        p.end()
    
    def paint(self, p, *args):
        p.drawPicture(0, 0, self.picture)
    
    def boundingRect(self):
        ## boundingRect _must_ indicate the entire area that will be drawn on
        ## or else we will get artifacts and possibly crashing.
        ## (in this case, QPicture does all the work of computing the bouning rect for us)
        return QtCore.QRectF(self.picture.boundingRect())

--------------------------------------------------------------------------------------    


dpoint = dpoint_var()
dpoint.new_dpoint()

item = CandlestickItem(dpoint_var.data2)
plt = pg.plot()
plt.addItem(item)
plt.setWindowTitle('pyqtgraph example: customGraphicsItem')


app = QtWidgets.QApplication(sys.argv)
timer = QtCore.QTimer()
timer.timeout.connect(dpoint.new_dpoint)
timer.start(1000)
w = MainWindow()
w.show()
sys.exit(app.exec_())

编辑：

多亏了MusicAmante的建议，我设法解决了错误。先生，谢谢您的宝贵建议:)

import pyqtgraph as pg
import numpy as np
from PyQt5 import QtWidgets, QtCore
from pyqtgraph import PlotWidget, plot, QtCore, QtGui
import sys 
import os
from random import randint

class Dpoint_var:
    dpoint = 20

    def __init__(self):
        def return_dpoint():
            data = np.empty((0,5), dtype = float)
            data2 = np.empty((0,5), dtype = float)
            return self.dpoint


    def new_dpoint(self):
        self.data = np.random.uniform(low=0.0005, high=0.01, size=(self.dpoint,5))
        self.data2 = np.empty((self.dpoint,5), dtype = float)
        #set the first column to an ordered number line
        x = 0
        for i in range(len(self.data[:,0])):
            self.data2[i][0] = x
            x += 1

        #set the second column to the opening data
        for i in range(len(self.data[:,1])):
            if i > 10:        
                self.data2[i][1] = self.data[i-10][1]
            else:
                self.data2[i][1] = self.data[i][1] 


        #set the third column to the closing data
        for i in range(len(self.data[:,2])):
            self.data2[i][2] = self.data[i][1]


        #set the fourth column to the minimum bat value for the time period
        for i in range(len(self.data[:,3])):
            if i > 10:
                self.data2[i][3] = self.data[i-10:i, 1].min()

            else:
                for i in range(len(self.data[:,3])):
                    self.data2[i][3] = self.data[i][3]

        #set the fourth column to the minimum bat value for the time period
        for i in range(len(self.data[:,4])):
            if i > 10:
                self.data2[i][4] = self.data[i-1:i, 1].max()

            else:
                for i in range(len(self.data[:,4])):
                    self.data2[i][4] = self.data[i][4]
        dpoint.dpoint +=1

## Create a subclass of GraphicsObject.
## The only required methods are paint() and boundingRect() 
## (see QGraphicsItem documentation)
class CandlestickItem(pg.GraphicsObject):
    def __init__(self, data):
        pg.GraphicsObject.__init__(self)
        self.data = data  ## data must have fields: time, open, close, min, max
        self.generatePicture()

    def generatePicture(self):
        ## pre-computing a QPicture object allows paint() to run much more quickly, 
        ## rather than re-drawing the shapes every time.
        self.picture = QtGui.QPicture()
        p = QtGui.QPainter(self.picture)
        p.setPen(pg.mkPen('w'))
        width = (self.data[1][0] - self.data[0][0]) / 3.
        for (t, open, close, min, max) in self.data:
            p.drawLine(QtCore.QPointF(t, min), QtCore.QPointF(t, max))
            if open > close:
                p.setBrush(pg.mkBrush('r'))
            else:
                p.setBrush(pg.mkBrush('g'))
            p.drawRect(QtCore.QRectF(t-width, open, width*2, close-open))
        p.end()

    def paint(self, p, *args):
        p.drawPicture(0, 0, self.picture)

    def boundingRect(self):
        ## boundingRect _must_ indicate the entire area that will be drawn on
        ## or else we will get artifacts and possibly crashing.
        ## (in this case, QPicture does all the work of computing the bouning rect for us)
        return QtCore.QRectF(self.picture.boundingRect())



dpoint = Dpoint_var()
dpoint.new_dpoint()

item = CandlestickItem(dpoint.data2)
plt = pg.plot()
plt.addItem(item)
plt.setWindowTitle('pyqtgraph example: customGraphicsItem')
app = QtWidgets.QApplication(sys.argv)

timer = QtCore.QTimer()
timer.timeout.connect(dpoint.new_dpoint)
timer.start(10)
sys.exit(app.exec_())
    

但是，我仍然很难找到更新图表的正确方法。 我希望TP能够从外部信号而不是QTimer更新图表，但是即使在QTimer中，我也找不到可以重新加载图表的正确语法。 据说计时器正在为数组添加新数据，但没有加载图表。 但是，我无法弄清楚这是这样做的。 QT库是如此之大，非结构化和深奥。

有建议吗？