Create Simple GUI with Matplotlib Sine Wave

Introduction

In this lab, you will learn how to create a simple GUI using Matplotlib's Button widget. The GUI will allow you to modify a sine wave by changing the frequency using the Next and Previous buttons.

VM Tips

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Import the necessary libraries

First, let's import the necessary libraries, including matplotlib.pyplot, numpy, and Button from matplotlib.widgets.

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.widgets import Button

Set up the initial plot

Next, we will set up the initial plot. We will create a sine wave with a frequency of 2 Hz using numpy's arange function, and plot it using matplotlib.pyplot's plot function.

freqs = np.arange(2, 20, 3)
fig, ax = plt.subplots()
t = np.arange(0.0, 1.0, 0.001)
s = np.sin(2*np.pi*freqs[0]*t)
l, = ax.plot(t, s, lw=2)

Create the button callback functions

Now, we will create two callback functions for the Next and Previous buttons. These functions will update the plot with a new sine wave with a different frequency.

class Index:
    ind = 0

    def next(self, event):
        self.ind += 1
        i = self.ind % len(freqs)
        ydata = np.sin(2*np.pi*freqs[i]*t)
        l.set_ydata(ydata)
        plt.draw()

    def prev(self, event):
        self.ind -= 1
        i = self.ind % len(freqs)
        ydata = np.sin(2*np.pi*freqs[i]*t)
        l.set_ydata(ydata)
        plt.draw()

callback = Index()

Create the Next and Previous buttons

Now, we will create the Next and Previous buttons using matplotlib.pyplot's add_axes function, and assign the callback functions we created earlier to them using on_clicked.

axprev = fig.add_axes([0.7, 0.05, 0.1, 0.075])
axnext = fig.add_axes([0.81, 0.05, 0.1, 0.075])
bnext = Button(axnext, 'Next')
bnext.on_clicked(callback.next)
bprev = Button(axprev, 'Previous')
bprev.on_clicked(callback.prev)

Display the plot

Finally, we will display the plot using matplotlib.pyplot's show function.

plt.show()

Summary

In this lab, you learned how to create a simple GUI using Matplotlib's Button widget. You learned how to modify a sine wave by changing the frequency using the Next and Previous buttons.