[英]How to optimise plotting Serial data in real-time using Python
我正在嘗試實時繪制從串行設備接收到的制表符分隔值。 我對 python 很陌生,但已經設法拼湊了一個管理它的腳本,但是它似乎無法處理接收數據的速率,並且在減速並最終凍結之前使用了大量處理能力。 我能做些什么來防止這種情況發生。 我附上了一個我正在使用的數據和我的腳本的例子
我收到的數據看起來像這樣,並且以每半秒大約一行的速度接收。
546 5986637 3598844 +26.0 01A0
547 5986641 3598843 +25.50 0198
548 5986634 3598844 +24.50 0188
from matplotlib import pyplot as plt
from matplotlib import animation
import serial
from pandas import DataFrame
from datetime import datetime
import csv
filename = datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p") # Gets time and date in readable format for filenaming.
Data1 = {'Value': [0], 'Frequency 1': [0], 'Frequency2': [0], 'Temperature': [0]}
df = DataFrame(Data1, columns=['Value', 'Frequency1', 'Frequency2', 'Temperature'])
serial_port = 'COM5'; # Different port for linux/mac
baud_rate = 9600; # In arduino, Serial.begin(baud_rate)
write_to_file_path = "output.txt";
data = []
ft = []
output_file = open(write_to_file_path, "w+");
ser = serial.Serial(serial_port, baud_rate)
plt.ion()
fig, (ax1, ax2, ax3) = plt.subplots(3, 1, sharex=True, sharey=False, )
ax1.set_title('Temp')
ax2.set_title('Freq 1')
ax3.set_title('Freq 2')
ax1.set_ylabel('Temperature')
ax2.set_ylabel('Frequency')
ax3.set_ylabel('Frequency')
ax1.ticklabel_format(useOffset=False)
ax2.ticklabel_format(useOffset=False)
ax3.ticklabel_format(useOffset=False)
ax1.ticklabel_format(style='plain', axis='y', scilimits=(0, 0))
ax2.ticklabel_format(style='sci', axis='y', scilimits=(6, 6))
ax3.ticklabel_format(style='sci', axis='y', scilimits=(6, 6))
while True:
line = ser.readline();
line = line.decode("utf-8") # ser.readline returns a binary, convert to string
print(line)
line1 = line.split('\t') # Separates values by tabs
output_file.write(line); # Writes to text file
data.append(line1) # Adds line to data file
newline = [float(line1[0]), float(line1[1]), float(line1[2]), float(line1[3])] # Creates line of float values
ft.append(newline) # Adds to list of floats
f1 = float(line1[0]) # Line number (count)
f2 = float(line1[1]) # Frequency 1
f3 = float(line1[2]) # Frequency 2
f4 = float(line1[3]) # Temperature in C
f5 = str(line1[4]) # Temperature in Hex, treated as a string
# Data2 = {'Value':[f1],'Frequency 1':[f2],'Frequency2':[f3], 'Temperature':[f4]}
# df2 = DataFrame(Data2,columns=['Value', 'Frequency1','Frequency2','Temperature'])
# df.append(df2)
# DataFrame still not working, need to fix so that data is stores as integer or float
plt.pause(0.1)
ax1.plot(f1, f4, marker='.', linestyle='solid') # subplot of freq 1
ax2.plot(f1, f2, marker='.', linestyle='solid') # subplot of freq 2
ax3.plot(f1, f3, marker='.', linestyle='solid') # subplot of Temp in C
plt.subplot
plt.xlabel("Count")
with open(filename + ".csv", "a") as f: # Writes data to CSV, hex values for temp don't seem to be writing
writer = csv.writer(f, delimiter=",")
writer.writerow([f1, f2, f3, f4, f5])
plt.draw()
plt.savefig(filename + '.png', bbox_inches='tight') # Saves the plot
您可以考慮使用線程來拆分您的任務。 您可能不需要每次收到新數據時都保存該圖。 例如,您可以通過僅每 30 秒左右更新一次圖來減少計算負載。 您還可以拆分寫入 csv,這樣您就有三個線程,一個查找數據,一個存儲緩沖數據,一個更新您的繪圖。
這個答案可能是一個很好的參考。
在 foo() 的末尾,創建一個 Timer,它會在 10 秒后調用 foo() 本身。 因為,Timer 創建了一個新線程來調用 foo()。
import time, threading
def foo():
print(time.ctime())
threading.Timer(10, foo).start()
foo()
#output:
#Thu Dec 22 14:46:08 2011
#Thu Dec 22 14:46:18 2011
#Thu Dec 22 14:46:28 2011
#Thu Dec 22 14:46:38 2011
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