如何保持实时图表仅查看最后 50 个数据点？

Question

这篇文章与我之前的问题有关。Updating Label and Live Graph dynamically using Arduino Data in Tkinter我的图表嵌入在 Tkinter 上。我使用的是相同的代码，但我意识到，虽然我的实时图表正在从来自 Arduino 的串行数据动态更新，但旧数据点仍在不断添加。我想查看要嵌入实时图表的最后 50 个数据点并删除旧数据点。我不知道如何操纵代码来完全实现我想要实现的目标。任何建议将不胜感激

代码如下：

#from tkinter import *
import tkinter as tk # proper way to import tkinter
import serial
import matplotlib
matplotlib.use("TkAgg")
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
from matplotlib.figure import Figure
import matplotlib.animation as animation
from matplotlib import style
style.use("ggplot")
import threading

class Dee(tk.Frame):
    def __init__(self, master=None, title='', ylabel='', label='', color='c', ylim=1, **kwargs):
        tk.Frame.__init__(self, master, **kwargs)
        self.data = []
        fig = Figure(figsize = (7,6))
        self.plot = fig.add_subplot(111)
        self.plot.set_title(title)
        self.plot.set_ylabel(ylabel)
        self.plot.set_ylim(0, ylim)
        self.line, = self.plot.plot([], [], color, marker = 'o',label = label)
        self.plot.legend(loc='upper left')

        label = tk.Label(self, text = ylabel, font = "Times 22 bold")
        label.grid(row = 0, column = 3)
        button_1 = tk.Button(self, text = "Back To Homepage", command = F1.tkraise)
        button_1.grid(row = 1, column = 2)
        label_1 = tk.Label(self, text = "Current Value: ", font = "Verdana 10 bold")
        label_1.grid(row = 2, column = 2)
        self.label_data = tk.Label(self, font = "Verdana 10")
        self.label_data.grid(row = 2, column = 3)
        canvas = FigureCanvasTkAgg(fig, master=self)
        canvas.get_tk_widget().grid(row = 3, column = 3)

        ani = animation.FuncAnimation(fig, self.update_graph, interval = 1000, blit = False)
        canvas.draw()

    def update_graph(self, i):
        if self.data:
        self.line.set_data(range(len(self.data)), self.data)
        self.plot.set_xlim(0, len(self.data))

    def set(self, value):
        self.data.append(value)
        self.label_data.config(text=value)

my_window = tk.Tk()
my_window.title("Graphical User Interface Demo#1")
my_window.geometry("720x720")

F1 = tk.Frame(my_window)
F2 = Dee(my_window, title='Temperature Graph', ylabel='Temperature', color='c', label='Degrees C', ylim=40)
F3 = Dee(my_window, title='Humidity Graph', ylabel='Humidity', color='g', label='Percentage %', ylim=100)
F4 = Dee(my_window, title='Solved Water Graph', ylabel='Water Volume', color='b', label='mL', ylim=55)

#For Frame One
label_1 = tk.Label(F1, text = "Homepage of GUI", font = "Times 22 bold")
label_1.grid(row = 0, column = 3)
button_1 = tk.Button(F1, text = "Page of Humidity", bd = 8, command = F2.tkraise)
button_1.grid(row = 1, column = 2)
button_2 = tk.Button(F1, text = "Page of Temperature", bd = 8, command = F3.tkraise)
button_2.grid(row = 1, column = 3)
button_3 = tk.Button(F1, text = "Page of Water",  bd = 8, command = F4.tkraise)
button_3.grid(row = 1, column = 4)

for frame in(F1, F2, F3, F4):
    frame.grid(row = 0, column = 0, sticky = "NSEW")

F1.tkraise()

def get_data():
    #Initialization of Serial Comm
    ser = serial.Serial('COM3', 9600)
    while True:
        pulldata = ser.readline().decode('ascii')
        get_data = pulldata.split(',')
        F2.set(int(get_data[0]))
        F3.set(int(get_data[1]))
        F4.set(int(get_data[2]))
        print(pulldata)

# start the thread that will poll the arduino
t = threading.Thread(target=get_data)
t.daemon = True
t.start()

my_window.mainloop()

Answer 1

要从数组中仅选择最后 n 个数据，请使用

data[-n:]

让绘图自动缩放使用

ax.autoscale()