How to plot square function with matplotlib

Question

I have an list of values that alternate between 0 and 1, eg [0,1,0,1,0] and I want to graph them so they appear as a square wave using matplotlib for python. I have this so far:

input_amp = [1,0,1,0,1,0,1,0,1,0]
plt.plot(input_amp, marker='d', color='blue')
plt.title("Waveform")
plt.ylabel('Amplitude')
plt.xlabel("Time")
plt.savefig("waveform.png")
plt.show()

This gives me an output like this this :

How do I make it so instead of going on an angle between the points the line stays flat?

I found this post but it deals more with an animation and not just plotting the function.

Thomas Lotze · Accepted Answer · 2016-02-23 14:01:54Z

17

The relevant bit from that post you reference is the drawstyle:

 plt.plot(input_amp, marker='d', color='blue', drawstyle='steps-pre')

answered Feb 23, 2016 at 14:01

Thomas Lotze

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Kyung Lee Over a year ago

drawstyle='steps-post' is more commonly used.

Alex Fedotov · Accepted Answer · 2021-02-05 23:32:37Z

-1

"Elementary, Watson!"

import matplotlib.pyplot as plot
import numpy as np

# Sampling rate 1000 hz / second
t = np.linspace(0, 1, 100, endpoint=True)

# Plot the square wave signal
plot.plot(t, signal.square(2 * np.pi * 1 * t))

# A title for the square wave plot
plot.title('1Hz square wave sampled at 100 Hz /second')

# x axis label for the square wave plot
plot.xlabel('Time')
    
# y axis label for the square wave plot
plot.ylabel('Amplitude')
plot.grid(True, which='both')

# Provide x axis and line color
plot.axhline(y=0, color='k')

# Set the max and min values for y axis
plot.ylim(-1.2, 1.2)

# Display the square wave
plot.show()

answered Feb 5, 2021 at 23:32

Alex Fedotov

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Mavis_Ackerman Over a year ago

The amplitude of this waveform is from 1 to -1. Can you please show how can extend this wave from 0 to 2 instead?

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