Question

基本上我想暂停我在这里设置的实况情节：

import serial
import numpy as np
from matplotlib import pyplot as plt
ser = serial.Serial('/dev/tty.usbmodemfa131', 9600)


#Setting up the animated plot
plt.ion() # set plot to animated
fig = plt.figure()

ydata = [0] * 100
ax1=plt.axes()  

# make plot
line, = plt.plot(ydata)
plt.ylim([24,29])

#Starting data collection
while True:
    rawData = ser.readline().rstrip()
    x = len(rawData)
    #print(floatData)
    if len(rawData) <= 6:
        try:
            data = float(rawData)
            if data <= 100:
                ydata.append(data)
                del ydata[0]
                line.set_xdata(np.arange(len(ydata)))
                line.set_ydata(ydata)  # update the data
                plt.draw() # update the plot
        except ValueError:
            print "Not a float"

我想暂停图中的情节，但由于数据正在流式传输，我无法弄清楚如何处理这个数字。

Answer 1

因此，对您的问题的一个很好的解决方案是使用线程来运行绘图窗口并通过主线程执行控制。这可以这样实现：

import serial
import numpy as np
from matplotlib import pyplot as plt
from threading import Thread,Event
import time

#A simple ring buffer to keep the plotting data in
class RingBuffer(object):
    def __init__(self,size):
        self.size = size
        self._size = 2*size
        self._buffer = np.zeros(self._size)
        self._idx = 0

    def insert(self,val):
        idx = self._idx%self.size
        self._buffer[idx] = val
        self._buffer[idx+self.size] = val
        self._idx+=1
        if self._idx > self.size:
            self._idx-=self.size

    def get(self):
        start_idx = (self._idx)%self.size
        end_idx = start_idx+self.size
        return self._buffer[start_idx:end_idx]

#A thread to handle plotting and reading data from the serial port
class Plotter(Thread):
    def __init__(self,stream,stop,pause):
        Thread.__init__(self)
        self.stream = stream
        self.fig = plt.figure()
        self.ax = plt.axes()
        self.size = 100
        self.xdata = np.arange(self.size)
        self.ydata = RingBuffer(self.size)
        self.line, = self.ax.plot(self.ydata.get())
        plt.ylim([24,29])                                                  
        self.stop = stop
    self.pause = pause

    #The main loop of the thread, invoked with .start()
    def run(self):
        while not self.stop.is_set():
            if self.pause.is_set():
                continue
            raw_data = self.stream.readline().rstrip()                     
            if len(raw_data) <= 6:
                try:
                    data = float(raw_data)
                except ValueError:
                    print "Not a float"
                else:
                    if data <= 100:
                        self.ydata.insert(data)
                        self.line.set_xdata(self.xdata)
                        self.line.set_ydata(self.ydata.get())
                        plt.draw()

            #sleep statement to reduce processor load 
        time.sleep(1) 

#this is implemented to facilitate use through something like Ipython easily
class Controller(object):
    def __init__(self):

        #These events control execution of the thread main loop
        self.stop = Event()
        self.pause = Event()
        self.stream = serial.Serial('/dev/tty.usbmodemfa131', 9600)
        self.plotter_thread = Plotter(self.stream,self.stop,self.pause)
        self.plotter_thread.start()

def main():
    con = Controller()

    #Loop over terminal input
    #possible commands are stop, pause and unpause
    while True:
        command = raw_input("cmd >>>")
        if command == "stop":
            con.stop.set()
            con.plotter_thread.join()
            break
        elif command == "pause":
            con.pause.set()
        elif command == "unpause":
            con.pause.clear()
        else:
            print "unrecognised command"

if __name__ == "__main__":
    main()

这应该为您提供一个命令行界面，如：

cmd >>>

以下任何陈述应控制绘图仪

cmd >>>pause
cmd >>>unpause
cmd >>>stop

在Python中绘制串行数据如何暂停matplotlib图？

1 个答案: