In this tutorial, we will introduce you how to draw a circle using python matplotlib. It is easy to use.
plt.Circle()
This function is defined as:
matplotlib.patches.Circle(xy, radius=5, **kwargs)
Here xy = (x, y), it will draw a true circle at center xy = (x, y) with given radius
We should notice: plt.Circle() is the child class of artist.Artist
Circle<–Ellipse<—Patch<—artist.Artist
It means we should use matplotlib.axes.Axes.add_artist() function to draw a circle.
Matplotlib draw a circle example 1
This example will draw a circle without creating an axis.
For example:
import numpy as np import matplotlib.pyplot as plt draw_circle = plt.Circle((0., 0.), 10, fill=False) print(type(draw_circle)) # <class 'matplotlib.patches.Circle'> plt.xlim(xmin=-15,xmax=15) plt.ylim(ymin=-15,ymax=15) plt.gcf().gca().add_artist(draw_circle) plt.show()
Run this code, we will see:
Here we have not created an axis, in order to get it, we use plt.gcf().gca() to get an axis on the current figure.
Matplotlib draw a circle example 2
If we have created an axis, we can do as follows:
import numpy as np
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
draw_circle = plt.Circle((0., 0.), 10, fill=False)
print(type(draw_circle)) # <class 'matplotlib.patches.Circle'>
plt.xlim(xmin=-15,xmax=15)
plt.ylim(ymin=-15,ymax=15)
ax.add_artist(draw_circle)
fig.suptitle('matplotlib draw a circle')
plt.show()
Run this code, we will see:
How about fill = True?
For example:
draw_circle = plt.Circle((0., 0.), 10, fill=True) print(type(draw_circle)) # <class 'matplotlib.patches.Circle'> plt.xlim(xmin=-15,xmax=15) plt.ylim(ymin=-15,ymax=15)
We will see:
How to change the color of a circle?
We can use some set methods to change the color of a circle.
For example:
draw_circle = plt.Circle((0., 0.), 10, fill=True)
draw_circle.set_facecolor("red")
draw_circle.set_edgecolor("green")
draw_circle.set_linewidth(5)
Run this code, we will see:
