Print continuous 4 line graphs Matplotlib

Thread Starter

Vindhyachal Takniki

Joined Nov 3, 2014
476
1. I have to print values of 4 different sensor taken at every 10 sec in line graph.
So I have used subplots to do so.
I took reading every 10 sec, plot them for 100 such readings & then close the graph & start over again.
This is continuous graph, i.e every 10 sec I read value, I have to print it & so on for 15 minutes.
It is not like I have values in array/list before printing the graph.

2. I had took reference from below links:
http://stackoverflow.com/questions/11874767/real-time-plotting-in-while-loop-with-matplotlib
http://pythonprogramming.net/matplotlib-tutorial-part-5-subplots-multiple-plots-figure/
http://stackoverflow.com/questions/8213522/matplotlib-clearing-a-plot-when-to-use-cla-clf-or-close


3. I am able to do so by scatter plot. My code is below. It has two files: main.py & graph.py.
main.py calls graph.py.

4. I am using python 2.7 & today I have downloaded matplotlib.
Attached is code file. It has two files in it.
Also code link is: http://www.docdroid.net/z5Ba1IS/graph.txt.html


problems:
1. In graph.py, I have function print_val(). In this I have called ax1.scatter() to print scatter graph.
I need to print line graph. if I replace it with ax1.plot(x,y), it don't print anything.
i have to do it by line graph. how to do that.

2. In graph.py functions, I have defined global variables as "global fig,rect,ax1,ax2,ax3,ax4,plt"
But they are not defined globally in file, but inside the functions.
I don't know somehow code is working.
Can someone suggest me the correct way to do that so that ax1 defined in init(), is same as in print_val().
I think classes would be correct option for this. But I have no experience of it.


3. in main.py, I have defined "except KeyboardInterrupt: graph.close(); GPIO.cleanup() ".
But when I exit the code by pressing ctrl+z , graph screen remains on screen.

4. While graph is plotting, if I minimize the graph screen & then maximize it.
Graph disappears from the open window & only grey screen appears.

Code:
/*************************main.py*******************************************************/

import time
import graph

hor_pixel = 0

while True:
    if(elapsed_time() >= 10):
           temp_list = read_sensor_data()   #contain 4 values in a list
           graph.print_val(temp_list , hor_pixel)
           hor_pixel = hor_pixel+1;
           if(hor_pixel >= 100):
            hor_pixel = 0
            graph.close();
            graph.init()
         
         
except KeyboardInterrupt:
    graph.close();
    GPIO.cleanup()
   
   
graph.close();
GPIO.cleanup()   
           

/*************************graph.py*******************************************************/


import matplotlib.pyplot as plt
import time


def init():
    global fig,rect,ax1,ax2,ax3,ax4,plt

    fig = plt.figure()
    rect = fig.patch
    rect.set_facecolor('#31312e')
    ax1 = fig.add_subplot(2,2,1, axisbg='grey')
    #ax1.plot(x, y, 'c', linewidth=3.3)
    ax1.set_xlim([0,100])
    ax1.set_ylim([0,100])
    ax1.tick_params(axis='x', colors='c')
    ax1.tick_params(axis='y', colors='c')
    ax1.spines['bottom'].set_color('w')
    ax1.spines['top'].set_color('w')
    ax1.spines['left'].set_color('w')
    ax1.spines['right'].set_color('w')
    ax1.yaxis.label.set_color('c')
    ax1.xaxis.label.set_color('c')
    ax1.set_title('Windspeed', color = 'c')
    ax1.set_xlabel('Read')
    ax1.set_ylabel('Value')

    ax2 = fig.add_subplot(2,2,2, axisbg='grey')
    #ax2.plot(x, y, 'c', linewidth=3.3)
    ax2.set_xlim([0,100])
    ax2.set_ylim([0,100])
    ax2.tick_params(axis='x', colors='c')
    ax2.tick_params(axis='y', colors='c')
    ax2.spines['bottom'].set_color('w')
    ax2.spines['top'].set_color('w')
    ax2.spines['left'].set_color('w')
    ax2.spines['right'].set_color('w')
    ax2.yaxis.label.set_color('c')
    ax2.xaxis.label.set_color('c')
    ax2.set_title('Rainfall', color = 'c')
    ax2.set_xlabel('Read')
    ax2.set_ylabel('Value')

    ax3 = fig.add_subplot(2,2,3, axisbg='grey')
    #ax3.plot(x, y, 'c', linewidth=3.3)
    ax3.set_xlim([0,100])
    ax3.set_ylim([-100,100])
    ax3.tick_params(axis='x', colors='c')
    ax3.tick_params(axis='y', colors='c')
    ax3.spines['bottom'].set_color('w')
    ax3.spines['top'].set_color('w')
    ax3.spines['left'].set_color('w')
    ax3.spines['right'].set_color('w')
    ax3.yaxis.label.set_color('c')
    ax3.xaxis.label.set_color('c')
    ax3.set_title('Temperature', color = 'c')
    ax3.set_xlabel('Read')
    ax3.set_ylabel('C')


    ax4 = fig.add_subplot(2,2,4, axisbg='grey')
    #ax4.plot(x, y, 'c', linewidth=3.3)
    ax4.set_xlim([0,100])
    ax4.set_ylim([0,100])
    ax4.tick_params(axis='x', colors='c')
    ax4.tick_params(axis='y', colors='c')
    ax4.spines['bottom'].set_color('w')
    ax4.spines['top'].set_color('w')
    ax4.spines['left'].set_color('w')
    ax4.spines['right'].set_color('w')
    ax4.yaxis.label.set_color('c')
    ax4.xaxis.label.set_color('c')
    ax4.set_title('Humidity', color = 'c')
    ax4.set_xlabel('Read')
    ax4.set_ylabel('Humidity')

    plt.ion()
    plt.show()


def print_val(temp_list , hor_var):
    global ax1,ax2,ax3,ax4,plt
           
    ax1.scatter(hor_var, temp_list[0])
    ax2.scatter(hor_var, temp_list[1])
    ax3.scatter(hor_var, temp_list[2])
    ax4.scatter(hor_var, temp_list[3])
    plt.draw()
    time.sleep(0.05)

   
def close():
    global plt
    plt.close()
 
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