How to Draw a Circle Using Matplotlib in Python?

A Circle is a mathematical figure formed by joining all points lying on the same plane and are at equal distance from a given point. We can plot a circle in python using Matplotlib. There are multiple ways to plot a Circle in python using Matplotlib. 

Method 1: Using matplotlib.patches.Circle() function.

Matplotlib has a special function matplotlib.patches.Circle() in order to plot circles. 

Syntax: class matplotlib.patches.Circle(xy, radius=5, **kwargs)

Example 1: Plotting a colored Circle using matplotlib.patches.Circle()

Python3

# Demonstrating use of matplotlib.patches.Circle() function
# to plot a colored Circle

import matplotlib.pyplot as plt

figure, axes = plt.subplots()
Drawing_colored_circle = plt.Circle(( 0.6 , 0.6 ), 0.2 )

axes.set_aspect( 1 )
axes.add_artist( Drawing_colored_circle )
plt.title( 'Colored Circle' )
plt.show()

Output:

Example 2: Plotting an un-colored Circle using matplotlib.patches.Circle()

Python3

# Demonstrating use of matplotlib.patches.Circle() function
# to plot an un-colored Circle

import matplotlib.pyplot as plt

figure, axes = plt.subplots()
Drawing_uncolored_circle = plt.Circle( (0.6, 0.6 ),
                                      0.3 ,
                                      fill = False )

axes.set_aspect( 1 )
axes.add_artist( Drawing_uncolored_circle )
plt.title( 'Circle' )
plt.show()

Output:

Method 2: Using Circle Equation

Example 1: Plotting a Circle using Parametric equation of a circle

Python3

# Program to plot a Circle
# using Parametric equation of a Circle

import numpy as np
import matplotlib.pyplot as plt

theta = np.linspace( 0 , 2 * np.pi , 150 )

radius = 0.4

a = radius * np.cos( theta )
b = radius * np.sin( theta )

figure, axes = plt.subplots( 1 )

axes.plot( a, b )
axes.set_aspect( 1 )

plt.title( 'Parametric Equation Circle' )
plt.show()

Output:

Example 2: Using Center-Radius form of a circle equation

Python3

# Program to plot a Circle
# using Center-Radius form of circle equation

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace( -0.7 , 0.7 , 150 )
y = np.linspace( -0.7 , 0.7 , 150 )

a, b = np.meshgrid( x , y )

C = a ** 2 + b ** 2 - 0.2

figure, axes = plt.subplots()

axes.contour( a , b , C , [0] )
axes.set_aspect( 1 )

plt.title( 'Center-Radius form Circle' )
plt.show()

Output:

Method 3: Using the Scatter Plot of points 

Example:

Python3

# Program to plot a Circle
# using Scatter plot of points

import matplotlib.pyplot as plt

plt.scatter( 0 , 0 , s = 7000 )
plt.title( 'Circle' )

plt.xlim( -0.85 , 0.85 )
plt.ylim( -0.95 , 0.95 )

plt.title( "Scatter plot of points Circle" )
plt.show()

Output: