Python - 实时绘图

Question

我写了一个简单的python脚本来显示我的传感器数据（从串行读取）。 我想了解当我点击任何地方时图形崩溃的原因... 是否有任何 - 如果可能，简单的方法 - 避免脚本崩溃，如果我尝试在计算机上执行其他操作？

此外，如果我想开发一个简单的GUI，有人学习如何做的例子？它会避免这个问题吗？

import serial 
import re 
import numpy as np 
import time 
from matplotlib import pyplot as plt 

SERIAL_PORT = 'COM3' 
BAUDRATE = 9600 
BUFFER_SIZE = 30 



print("initialisation ...") 
ser = serial.Serial(SERIAL_PORT, BAUDRATE) 
buffer = [] 

plt.ion() 
fig = plt.figure() 
ydata = [0]*BUFFER_SIZE*2 
prevBuf = [0]*BUFFER_SIZE*10 
ax1=plt.axes() 

line, = plt.plot(prevBuf) 
plt.ylim([2000,10000]) 


def clean_serial(): 
    i=0 
    while i<=5: 
     data = ser.readline() 
     print data 
     i+=1 
    ser.flush() 


def extract_number(rawdata): 
    return float(re.sub("[^0-9.]", " ", rawdata)) 

def process_buffer(buf): 

    prevBuf[len(prevBuf)-BUFFER_SIZE:] = buf 

    line.set_xdata(np.arange(len(prevBuf))) 
    line.set_ydata(prevBuf) 

    ydataMax = max(prevBuf)+10 
    ydataMin = min(prevBuf)-100 
    plt.ylim([ydataMin,ydataMax]) 
    plt.draw() 


    prevBuf[:] = prevBuf[BUFFER_SIZE:]+buf 

print("cleaning serial") 
clean_serial() 

print("reading value from serial") 
while True: 
    data = extract_number(ser.readline()) 
    buffer.append(data) 
    if len(buffer)>= BUFFER_SIZE: 
     process_buffer(buffer) 
     buffer=[] 


ser.close() 

其输出：script crashing

谢谢！

Answer 1

我写了一个Python应用程序可能对您有用：

################################################################### 
#                 # 
#      PLOTTING A LIVE GRAPH      # 
#     ----------------------------     # 
#   EMBED A MATPLOTLIB ANIMATION INSIDE YOUR    # 
#   OWN GUI!            # 
#                 # 
################################################################### 


import sys 
import os 
from PyQt4 import QtGui 
from PyQt4 import QtCore 
import functools 
import numpy as np 
import random as rd 
import matplotlib 
matplotlib.use("Qt4Agg") 
from matplotlib.figure import Figure 
from matplotlib.animation import TimedAnimation 
from matplotlib.lines import Line2D 
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas 
import time 
import threading 



def setCustomSize(x, width, height): 
    sizePolicy = QtGui.QSizePolicy(QtGui.QSizePolicy.Fixed, QtGui.QSizePolicy.Fixed) 
    sizePolicy.setHorizontalStretch(0) 
    sizePolicy.setVerticalStretch(0) 
    sizePolicy.setHeightForWidth(x.sizePolicy().hasHeightForWidth()) 
    x.setSizePolicy(sizePolicy) 
    x.setMinimumSize(QtCore.QSize(width, height)) 
    x.setMaximumSize(QtCore.QSize(width, height)) 

'''''' 

class CustomMainWindow(QtGui.QMainWindow): 

    def __init__(self): 

     super(CustomMainWindow, self).__init__() 

     # Define the geometry of the main window 
     self.setGeometry(300, 300, 800, 400) 
     self.setWindowTitle("my first window") 

     # Create FRAME_A 
     self.FRAME_A = QtGui.QFrame(self) 
     self.FRAME_A.setStyleSheet("QWidget { background-color: %s }" % QtGui.QColor(210,210,235,255).name()) 
     self.LAYOUT_A = QtGui.QGridLayout() 
     self.FRAME_A.setLayout(self.LAYOUT_A) 
     self.setCentralWidget(self.FRAME_A) 

     # Place the zoom button 
     self.zoomBtn = QtGui.QPushButton(text = 'zoom') 
     setCustomSize(self.zoomBtn, 100, 50) 
     self.zoomBtn.clicked.connect(self.zoomBtnAction) 
     self.LAYOUT_A.addWidget(self.zoomBtn, *(0,0)) 

     # Place the matplotlib figure 
     self.myFig = CustomFigCanvas() 
     self.LAYOUT_A.addWidget(self.myFig, *(0,1)) 

     # Add the callbackfunc to .. 
     myDataLoop = threading.Thread(name = 'myDataLoop', target = dataSendLoop, args = (self.addData_callbackFunc,)) 
     myDataLoop.start() 

     self.show() 

    '''''' 


    def zoomBtnAction(self): 
     print("zoom in") 
     self.myFig.zoomIn(5) 

    '''''' 

    def addData_callbackFunc(self, value): 
     # print("Add data: " + str(value)) 
     self.myFig.addData(value) 



''' End Class ''' 


class CustomFigCanvas(FigureCanvas, TimedAnimation): 

    def __init__(self): 

     self.addedData = [] 
     print(matplotlib.__version__) 

     # The data 
     self.xlim = 200 
     self.n = np.linspace(0, self.xlim - 1, self.xlim) 
     a = [] 
     b = [] 
     a.append(2.0) 
     a.append(4.0) 
     a.append(2.0) 
     b.append(4.0) 
     b.append(3.0) 
     b.append(4.0) 
     self.y = (self.n * 0.0) + 50 

     # The window 
     self.fig = Figure(figsize=(5,5), dpi=100) 
     self.ax1 = self.fig.add_subplot(111) 


     # self.ax1 settings 
     self.ax1.set_xlabel('time') 
     self.ax1.set_ylabel('raw data') 
     self.line1 = Line2D([], [], color='blue') 
     self.line1_tail = Line2D([], [], color='red', linewidth=2) 
     self.line1_head = Line2D([], [], color='red', marker='o', markeredgecolor='r') 
     self.ax1.add_line(self.line1) 
     self.ax1.add_line(self.line1_tail) 
     self.ax1.add_line(self.line1_head) 
     self.ax1.set_xlim(0, self.xlim - 1) 
     self.ax1.set_ylim(0, 100) 


     FigureCanvas.__init__(self, self.fig) 
     TimedAnimation.__init__(self, self.fig, interval = 50, blit = True) 

    def new_frame_seq(self): 
     return iter(range(self.n.size)) 

    def _init_draw(self): 
     lines = [self.line1, self.line1_tail, self.line1_head] 
     for l in lines: 
      l.set_data([], []) 

    def addData(self, value): 
     self.addedData.append(value) 

    def zoomIn(self, value): 
     bottom = self.ax1.get_ylim()[0] 
     top = self.ax1.get_ylim()[1] 
     bottom += value 
     top -= value 
     self.ax1.set_ylim(bottom,top) 
     self.draw() 


    def _step(self, *args): 
     # Extends the _step() method for the TimedAnimation class. 
     try: 
      TimedAnimation._step(self, *args) 
     except Exception as e: 
      self.abc += 1 
      print(str(self.abc)) 
      TimedAnimation._stop(self) 
      pass 

    def _draw_frame(self, framedata): 
     margin = 2 
     while(len(self.addedData) > 0): 
      self.y = np.roll(self.y, -1) 
      self.y[-1] = self.addedData[0] 
      del(self.addedData[0]) 


     self.line1.set_data(self.n[ 0 : self.n.size - margin ], self.y[ 0 : self.n.size - margin ]) 
     self.line1_tail.set_data(np.append(self.n[-10:-1 - margin], self.n[-1 - margin]), np.append(self.y[-10:-1 - margin], self.y[-1 - margin])) 
     self.line1_head.set_data(self.n[-1 - margin], self.y[-1 - margin]) 
     self._drawn_artists = [self.line1, self.line1_tail, self.line1_head] 



''' End Class ''' 


# You need to setup a signal slot mechanism, to 
# send data to your GUI in a thread-safe way. 
# Believe me, if you don't do this right, things 
# go very very wrong.. 
class Communicate(QtCore.QObject): 
    data_signal = QtCore.pyqtSignal(float) 

''' End Class ''' 



def dataSendLoop(addData_callbackFunc): 
    # Setup the signal-slot mechanism. 
    mySrc = Communicate() 
    mySrc.data_signal.connect(addData_callbackFunc) 

    # Simulate some data 
    n = np.linspace(0, 499, 500) 
    y = 50 + 25*(np.sin(n/8.3)) + 10*(np.sin(n/7.5)) - 5*(np.sin(n/1.5)) 
    i = 0 

    while(True): 
     if(i > 499): 
      i = 0 
     time.sleep(0.1) 
     mySrc.data_signal.emit(y[i]) # <- Here you emit a signal! 
     i += 1 
    ### 
### 




if __name__== '__main__': 
    app = QtGui.QApplication(sys.argv) 
    QtGui.QApplication.setStyle(QtGui.QStyleFactory.create('Plastique')) 
    myGUI = CustomMainWindow() 


    sys.exit(app.exec_()) 

'''''' 

只是尝试一下。将这些代码复制粘贴到一个新的python文件中，然后运行它。你应该得到一个漂亮的，平滑移动图形：

的实际数据在dataSendLoop（..）函数发送。这个函数在一个单独的线程中运行。请注意，数据在该功能中的代码行中发送：

mySrc.data_signal.emit(...) 

只需将要添加的括号内的值。下一次刷新屏幕时，该值将被添加到移动图形中。