Python_01h

Simple plotting

This is the simplest example of plotting a line on a graph - combined with adding another line to the same graph - and plotting a third line on a separate axis

We start by importing matplotlib.pyplot which I use because it makes simple plotting in Python feel familiar to Matlab users

We also import numpy to do the maths

# use libraries for maths functions

# and Matlab style plotting

import numpy as np

import matplotlib.pyplot as plt

Next we generate three simple sine wave signals of different frequencies and offset the second one on the Y axis. We call these s1 and s2 and s3 

# three example sinewaves

t = np.arange(0.0, 5.0, 0.01)

s1 = np.cos(2*np.pi*t)

s2 = np.sin(4*np.pi*t)+2

s3 = np.sin(8*np.pi*t)

Finally we plot two signals on the same axis and the third on a separate axis. 

# start new figure and plot both lines on it

plt.figure()

plt.plot(s1)

plt.plot(s2)

plt.show

#start new figure and plot third line on it

plt.figure()

plt.plot(s3)

plt.show