Matplotlib – Textbox Widgets

In this article, we are going to see matplotlib’s textbox widget. Matplotlib is a plotting library for the Python programming language. In this article, we will try to plot a graph for different powers(e.g. t^2, t^3, t^9, etc.) using textbox widget.

The Textbox is a widget that accepts input from the user. Input can also be formulas so that we can generate a graph based on those formulas. To use this widget we use TextBox() function. 

It accepts two parameters

• Figure i.e. graph to use.
• Text to display with textbox i.e. Label to textBox.

Below is the implementation of this widget:

Python

# Import modules
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import TextBox

# Adjust illustration
fig, ax = plt.subplots()
fig.subplots_adjust(bottom=0.2)

t = np.arange(-4.0, 4.0, 0.01)
l, = ax.plot(t, np.zeros_like(t), lw=2)

# Function to plot graph
# according to expression
def visualizeGraph(expr):
    ydata = eval(expr)
    l.set_ydata(ydata)
    ax.relim()
    ax.autoscale_view()
    plt.draw()

# Adding TextBox to graph
graphBox = fig.add_axes([0.1, 0.05, 0.8, 0.075])
txtBox = TextBox(graphBox, "Plot: ")
txtBox.on_submit(visualizeGraph)
txtBox.set_val("t**5")

# Plot graph
plt.show()

Output:

Explanation:

In the above program, we created a graph for t² as by default graph. In txtBox labelled as Plot: we can enter the formula we want to view the graph for.