How to Add Labels in a Plot using Python?

Last Updated : 06 Dec, 2022

In this article, we will discuss adding labels to the plot using Matplotlib in Python. But first, understand what are labels in a plot. The heading or sub-heading written at the vertical axis (say Y-axis) and the horizontal axis(say X-axis) improves the quality of understanding of plotted stats.

Example: Let's create a simple plot

Python

# python program to plot graph without labels
import matplotlib
import matplotlib.pyplot as plt
import numpy as np


# it will take x coordinates by default 
# starting from 0,1,2,3,4...
y = np.array([3, 8, 1, 10])

plt.plot(y)
plt.show()

Output:

Creating Labels for a Plot

By using pyplot() function of library we can add xlabel() and ylabel() to set x and y labels.

Example: Let's add Label in the above Plot

Python

# python program for plots with label
import matplotlib
import matplotlib.pyplot as plt
import numpy as np


# Number of children it was default in earlier case
x = np.array([0, 1, 2, 3])

# Number of families
y = np.array([3, 8, 1, 10])

plt.plot(x, y)

# Label for x-axis
plt.xlabel("Number of Childrens")

# Label for y-axis
plt.ylabel("Number of Families")

plt.show()  # for display

Output:

If you would like to make it more understandable, add a Title to the plot, by just adding a single line of code.

plt.title("Survey Of Colony")

Example:

Python3

# python program for plots with label
import matplotlib
import matplotlib.pyplot as plt
import numpy as np


# Number of children it was default in earlier case
x = np.array([0, 1, 2, 3])

# Number of families
y = np.array([3, 8, 1, 10])

plt.plot(x, y)

# Label for x-axis
plt.xlabel("Number of Childrens")

# Label for y-axis
plt.ylabel("Number of Families")

# title of the plot
plt.title("Survey Of Colony")

plt.show()  # for display

Output:

Set Font Properties for Titles and Labels

In order to make the Plot more attractive use the fontdict parameter in xlabel(), ylabel(), and title() to apply the font properties.

Python

# Adding font properties to labels and titles
import matplotlib
import matplotlib.pyplot as plt
import numpy as np


# Number of Children
x = np.array([0, 1, 2, 3])

# Number of Families
y = np.array([3, 8, 1, 10])

# label including this form1 will have these properties
form1 = {'family': 'serif', 'color': 'blue', 'size': 20}

# label including this form2 will have these properties
form2 = {'family': 'serif', 'color': 'darkred', 'size': 15}

plt.plot(x, y)
plt.xlabel("Number of Childrens", fontdict=form1)
plt.ylabel("Number of Families", fontdict=form1)
plt.title("Survey Of Colony", fontdict=form2)
plt.show()