CODEWITHSUNDEEP
python
Simrandeep Bahal
Simrandeep Bahal

Reputation: 119

Drawing circles in Python

I have the coordinates of the centre of circles and also their radii stored in an array. Now I want to make circles with their centres at the respective (x,y) location with the respective radius. I want all the circles to be made in the same 2D figure. The radii of the circles are different. How can I draw all the circles in the same figure in Python?

Upvotes: 0

Views: 27290

Answers (2)

Jllaher
Jllaher

Reputation: 31

I propose a solution, that is very simple and gives you the right result. The main advantage is, that it can be easily modified, like making wiggly circles, points on the circles, etc. Plus, no additional packages are needed.

import numpy as np
import matplotlib.pyplot as plt

M = 1000
angle = np.exp(1j * 2 * np.pi / M)
angles = np.cumprod(np.ones(M + 1) * angle)
x, y = np.real(angles), np.imag(angles)
plt.plot(x, y)

You can change the radius of the circle by multiplying x and y with the radius r value, and you can move the circle by adding coordinates X and Y

plt.plot(X + r * x, Y + r * y)

Notice, that x and y have to be defined only once.

Upvotes: 3

Calaf
Calaf

Reputation: 1173

You can use Turtle. Here is a simple example:

import turtle 
    
t = turtle.Turtle()

#This function draw a circle in x,y of radius r
def drawCircle(x,y,r):
    t.pu()
    t.goto(x,y-r) #-r because we want xy as center and Turtles starts from border
    t.pd()
    t.circle(r)


#draw a circle in (50,30) with r=50
drawCircle(50,30,50)

#draw a circle in (20,50) with r=100
drawCircle(20,50,100)

#draw a circle in (0,0) with r=10
drawCircle(0,0,10) #0,0 is the center of the screen

This will be your output: Note that the point (0,0) is the center of the screen. It uses Cartesian coordinates!

output

You can also change a lot of graphics things (color, line-width, etch...) in Turtle. See the documentation.

UPDATE

Your dimensions cannot be in micro meter: when you draw using Turtle or any other library the dimensions are espressed in pixels! If you want to use other measure unit, you have to convert all your values (x, y and r) in the new measure unit.

If you just want to zoom the image, try to multiply x,y and r for a fixed number. Let's do an example:

import turtle 
    
t = turtle.Turtle()
t.hideturtle() #this hides the arrow
t.speed(0) #turn off animation

#This function draw a circle in x,y of radius r zoomed by a n factor
def drawZoomedCircle(x,y,r,n):
    t.pu()
    t.goto(x*n,(y-r)*n) #-r because we want xy as center and Turtles starts from border
    t.pd()
    t.circle(r*n)

n=1

drawZoomedCircle(5,3,1,n)
drawZoomedCircle(2,5,3,n)
drawZoomedCircle(0,0,0.2,n)

The number n is a "zoom factor". When n=1 you have:

example 1

"Ehy! I can't see anything!"

Keep calm and try with n=50:

example 2

Now you can see all circles, also the smallest in 0,0 with r=0.2. You can use this principle to zoom your circles.

Upvotes: 2

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