Matplotlib - Text

Quiz

Matplotlib offers robust text support for creating and customizing text in plots, offering flexibility and control over various text properties. Includes features like writing mathematical expressions, font customization, newline-separated text with arbitrary rotations, and Unicode support. Below is the reference image that shows how to use text in Matplotlib plots −

To maintain consistency between on-screen and hard copy outputs, Matplotlib embeds fonts directly into documents.

This text support extends to both implicit and explicit interfaces. The implicit API involves functions like text, annotate, xlabel, ylabel, title, figtext, and suptitle. The explicit API uses functions like text, annotate, set_xlabel, set_ylabel, set_title, text, and suptitle.

Each function returns a Text instance that can be customized with different fonts and properties.

Writing Text as Title

To write text or specify titles for the entire figure or individual subplots, you can use the suptitle function at the figure level and the set_title function at the subplot (Axes) level, respectively.

Example

This example demonstrates the basics of creating a plot with a figure suptitle and axes title.

import matplotlib.pyplot as plt
import numpy as np

# Generate data
x_values = np.linspace(0.0, 5.0, 100)
y_values = np.cos(2 * np.pi * x_val`ues) * np.exp(-x_values)

# Create a plot
fig, ax = plt.subplots(figsize=(7, 4))
fig.subplots_adjust(bottom=0.15, left=0.2)
ax.plot(x_values, y_values)

# Add titles to the figure and axes
fig.suptitle('Figure Suptitle', fontsize=14, fontweight='bold')
ax.set_title('Axes Title')

# Display the plot
plt.show()

Output

On executing the above code we will get the following output −

Text is added successfully to the figure and subplot...

Adding Text as Labels for Axes

For labeling or adding text to the x-axis and y-axis, you can use the functions xlabel, ylabel for the implicit interface and set_xlabel, set_ylabel for the explicit interface.

Example

This example demonstrates the basics of Specifying labels for the x- and y-axis.

import matplotlib.pyplot as plt
import numpy as np

# Generate data
x_values = np.linspace(0.0, 5.0, 100)
y_values = np.cos(2 * np.pi * x_values) * np.exp(-x_values)

# Create a plot
fig, ax = plt.subplots(figsize=(7, 4))
fig.subplots_adjust(bottom=0.15, left=0.2)
ax.plot(x_values, y_values)

# Add labels to the x-axis and y-axis
ax.set_xlabel('X-Axis Label')
ax.set_ylabel('Y-Axis Label')

# Display the plot
plt.show()
print('Labels added successfully to the x-axis and y-axis...')

Output

On executing the above code we will get the following output −

Labels added successfully to the x-axis and y-axis...

Mathematical Expressions & Unicode Text

By using the text function, it becomes possible to write mathematical expressions and Unicode text at any location within the Axes.

Example

The following example demonstrates the integration of mathematical expressions and Unicode text within the plot. Here the text will add into a rectangle box by specifying the "bbox={'facecolor': 'red', 'alpha': 0.5, 'pad': 10}" values to the bbox parameter of the axes.text() method.

import matplotlib.pyplot as plt

# Create a subplot 
fig, ax = plt.subplots(figsize=(7, 4))
fig.subplots_adjust(top=0.85)

# Set the figure suptitle
fig.suptitle('Exploring Mathematical Expressions and Unicode Text')

# Set both x- and y-axis limits to [0, 10] instead of the default [0, 1]
ax.axis([0, 10, 0, 10])

# Add text with Mathematical Expression
ax.text(1.5, 7, "Einstein's energy-mass equivalence equation: $E=mc^2$",
        bbox={'facecolor': 'red', 'alpha': 0.5, 'pad': 10},
        style='italic')

# Add Unicode text with specified color and font size
ax.text(3, 5, 'Unicode: pTHn', color='green', fontsize=15)

# Display the plot
plt.show()
print('Successfully created a plot with Mathematical expressions and Unicode Text.')

Output

On executing the above code we will get the following output −

Successfully created a plot with Mathematical expressions and Unicode Text.

Plotting Animated Text

Text animations can be created to dynamically display changing text content or properties over time.

Example

This example demonstrates how to create a simple animation in Matplotlib by updating the properties of text within a plot.

from matplotlib import animation
import matplotlib.pyplot as plt

# Adjust figure size and autolayout
plt.rcParams["figure.figsize"] = [7.00, 3.50]
plt.rcParams["figure.autolayout"] = True

# Create figure and axes
fig = plt.figure()
ax = fig.add_subplot(111)

# Initial text
text = 'You are welcome!'
txt = ax.text(.20, .5, text, fontsize=15)

# Define colors for animation
colors = ['#1f77b4', '#ff7f0e', '#2ca02c', '#d62728', '#9467bd', '#8c564b', '#e377c2',    '#7f7f7f', '#bcbd22', '#17becf']

# Define animation function
def animate(num):
    txt.set_fontsize(num * 2 + num)
    txt.set_color(colors[num % len(colors)])
    return txt,

# Create animation
anim = animation.FuncAnimation(fig, animate, frames=len(text) - 1, blit=True)

# Display animation
plt.show()

Output

On executing the above code you will get the following output −

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