使用PyQtGraph繪制數據滾動圖形（4）

app = pg.QtGui.QApplication([])
win = pg.GraphicsWindow(title="數據滾動")
win.resize(600,300)

p = win.addPlot()
# Use automatic downsampling and clipping to reduce the drawing load
p.setDownsampling(mode='peak')
p.setClipToView(True)
curve = p.plot()

data = np.empty(100)
ptr = 0

def update():
    global data, ptr
    data[ptr] = np.random.normal()
    ptr += 1
    
    if ptr >= data.shape[0]: #當ptr大於等於data的長度時，改變data的長度
        tmp = data
        data = np.empty(data.shape[0] * 2)
        data[:tmp.shape[0]] = tmp
    
    curve.setData(data[:ptr])
    
timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(100)

app.exec_()

以上的圖形中包含從“0”時刻開始的所有數據，隨着數據的不斷增加，坐標也隨之變化。

app = pg.QtGui.QApplication([])
win = pg.GraphicsWindow(title="數據滾動")
win.resize(600,300)


p = win.addPlot()
# Use automatic downsampling and clipping to reduce the drawing load
p.setDownsampling(mode='peak')
p.setClipToView(True)
p.setRange(xRange=[-100,0])#將橫坐標的范圍限定為[-100,0]
p.setLimits(xMax=0)# 橫坐標的最大值為0
curve = p.plot()

data = np.empty(100)
ptr = 0

def update():
    global data, ptr
    data[ptr] = np.random.normal()
    ptr += 1
    
    if ptr >= data.shape[0]:
        tmp = data
        data = np.empty(data.shape[0] * 2)
        data[:tmp.shape[0]] = tmp
    
    
    curve.setData(data[:ptr])
    curve.setPos(-ptr, 0)#

        
timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(100)

app.exec_()