Difficulty with annotate function in Python 2

Question

I'm trying to plot live data on Python from an arduino through the serial port.

I found some difficulties with the annotate function: I don't know how to configure it or whether the place where I have put the annotate function is the right place or not.

import serial
import time
import numpy
import matplotlib.pyplot as plt
from drawnow import *

temperature= []
vitesse= []
charge= []
current= []
Time = []
cnt=0

# Create our serial object
arduinoData = serial.Serial('com5', 9600) 

# Turn on matplotlib interactive mode to plot live data
plt.ion() 

##fig1 = plt.figure()
STARTINGTIME = round(time.time(),2)

# A function that makes our desired plot
def makeFig(): 
    plt.subplot(2,2,1)
    plt.subplot(2,2,1).annotate(str(temperature)+','+ str(Time), 
                                textcoords='offset points')
    plt.title('Live Streaming Temperature Sensor Data')
    plt.ylabel('Temperature C')
    plt.grid(True)
    plt.plot(temperature, 'ro-')

    plt.subplot(2,2,2)
    plt.subplot(2,2,2).annotate(str(vitesse)+','+ str(Time), 
                                textcoords='offset points')
    plt.title('Live Streaming Speed Sensor Data')
    plt.ylabel('Speed KM/H')
    plt.grid(True)
    plt.plot(vitesse, 'bo-')

    plt.subplot(2,2,3)
    plt.subplot(2,2,3).annotate(str(charge)+','+ str(Time), 
                                textcoords='offset points')
    plt.title('Live Streaming SOC Sensor Data')
    plt.ylabel('Battery Charge %')
    plt.grid(True)
    plt.plot(charge, 'go-')

    plt.subplot(2,2,4)
    plt.subplot(2,2,4).annotate(str(current)+','+ str(Time), 
                                textcoords='offset points')
    plt.title('Live Streaming Current Sensor Data')
    plt.ylabel('Current A')
    plt.grid(True)
    plt.plot(current, 'yo-')

while True:

    while (arduinoData.inWaiting()==0): 
        # Wait here until there is data
        pass

    # Read the line of text from the serial port
    arduinoString = arduinoData.readline() 
    # Split it into an array
    dataArray = arduinoString.split(';')   
    temp = float(dataArray[0])
    vite = float(dataArray[1])
    char = float(dataArray[2])
    curr = float(dataArray[3])

    # Build our temperature array by appending temperature readings
    temperature.append(temp) 
    # Build our vitesse array by appending temp readings
    vitesse.append(vite)                    
    # Build our charge array by appending temp readings 
    charge.append(char)                     
    # Build our current array by appending temp readings
    current.append(curr)                     

    Time.append(round(time.time(),2) - STARTINGTIME)

    # Update our live graph
    drawnow(makeFig)                       

    plt.pause(0.00001)
    cnt += 1
    if(cnt > 50):
        temperature.pop(0)
        vitesse.pop(0)
        charge.pop(0)
        current.pop(0)

give me error a = mtext.Annotation(*args, **kwargs) TypeError: __init__() takes at least 3 arguments (3 given) — Soufiane Gaizen, Aug 11 '15 at 10:30
Do you want a label for every data point? For example, for every point in `temperature`, you want the value to be printed next to the point? — tmdavison, Aug 11 '15 at 10:49

Amy Teegarden · Answer 1 · 2015-08-12T18:53:31.923

0

annotate takes at least two arguments. The first is the text and the second is a tuple containing the coordinates where you want the text to go. Additionally, since you want to annotate every point, you will need to call annotate inside a loop.

Here's an example:

import matplotlib.pyplot as plt
import numpy as np
Y = np.sin(np.linspace(0, 3, 10))
plt.plot(Y)
for i, y in enumerate(Y):
    plt.annotate(str(y), (i, y))
plt.show()

Here's where the loop should go in your code:

def makeFig(): #Create a function that makes our desired plot

    plt.subplot(2,2,1)
    plt.title('Live Streaming Temperature Sensor Data')
    plt.ylabel('Temperature C')
    plt.grid(True)
    plt.plot(temperature, 'ro-')
    for i, t in enumerate(temperature):
        plt.annotate(str(t), (i, t), textcoords='offset points')

edited Aug 12 '15 at 18:53

answered Aug 11 '15 at 19:33

Amy Teegarden

3,842
20
23

thanks a lot but i don't have a function to be plotted like you have i plot point by point – Soufiane Gaizen Aug 12 '15 at 11:48
That does not matter. Y is a numpy array. You iterate over anything with a for loop. – Joonazan Aug 12 '15 at 12:10
what I'm suppose to put inside enumerate() – Soufiane Gaizen Aug 12 '15 at 15:44
Any iterable. For example, temperature, or current. – Amy Teegarden Aug 12 '15 at 16:52
What's the first element in temperature? – Amy Teegarden Aug 12 '15 at 17:02
it's a live plot i don't know what's the first element (i'm trying to plot sensors data) – Soufiane Gaizen Aug 12 '15 at 17:08
I meant what type is it, but looking at your code, it should be a float. I don't know why you'd get a value error. Is the the for loop line that's doing it? – Amy Teegarden Aug 12 '15 at 17:23
my code work fine but when i add the loop i get value error i think because i don't put the loop in the right place or samething like this – Soufiane Gaizen Aug 12 '15 at 17:34
I edited my answer to show you where it should go. See if that works. – Amy Teegarden Aug 12 '15 at 18:54
thank's amy it works but the numbers are plotted randomly – Soufiane Gaizen Aug 13 '15 at 11:19
@SoufianeGaizen What do you mean by randomly? It would help if you posted an image. – Amy Teegarden Aug 13 '15 at 21:08
randomly like this the value of graph 3 and 4 are plotted on graph 1 and 2 the value of graph 1 and 2 are out of the frame i want to post an images but i get you need at least 10 reputation to post images – Soufiane Gaizen Aug 14 '15 at 10:35

Difficulty with annotate function in Python 2

1 Answers1