Python Turtle is a drawing tool based on Logo, an educational programming language developed in the 1960s. Logo was used widely in school computer labs in the '80s and '90s.
Here's how it works: The user types lines of code to control a cursor onscreen, typically represented as a turtle. The turtle can draw lines and curves as it walks around, creating geometric art. The next step is to add a loop to your code, letting you repeat the instructions as many times as you want.
We'll be using Python, a programming language that comes preinstalled with many computer operating systems. Python is really cool! It's relatively easy to learn, and it's used widely by scientists, web developers, hackers, and just about everyone else.
In this workshop we'll be focusing on turtle, a module that comes built-in with Python.
We'll also use IDLE, a program that lets you write and run Python code.
At the Iffy Books computer lab we're using the Linux-based operating system Ubuntu. If you're getting started on your home computer, skip ahead to the section titled Using Python Turtle at Home. Once Python 3, IDLE, and Tkinter are installed, you can resume here.
❏ Start by opening the terminal application. Click the grid icon at the bottom left corner of the screen and search for "terminal," or click the terminal icon in the application bar.
❏ Type idle in the terminal and press enter to launch IDLE.
↳ If you're using macOS, you may need to use the command idle3instead.
When IDLE launches, you'll see a command prompt with three angle brackets (>>>) on the left side.
❏ In the Idle command prompt, type the following command and press enter. Nothing will happen, which is normal.
from turtle import *
You've just imported a collection of functions from the turtle module, which we'll be using for the rest of this workshop.
❏ Type the command below and press enter. You'll see a window pop up with a tiny turtle on a white background.
shape('turtle')
❏ Run this command to make the turtle walk forward 100 steps, leaving a line behind it as it goes:
forward(100)
❏ Now use the left() function to make your turtle turn left 90 degrees.
left(90)
❏ Walk forward another 100 steps with forward().
forward(100)
❏ If you want to reset everything and go back to the beginning, you can use reset().
reset()
❏ Try using right(90) and back(100) and see what happens. Now try right(360) and back(600).
❏ Drawing a square or rectangle.
❏ Draw an equilateral triangle (all three sides the same length).
So far your turtle has been in pen down mode, which means it draws a line wherever it goes. Next you'll learn to use pen up mode to move around without leaving a mark. You'll also learn to draw circles.
❏ Run the reset() command to clear the canvas.
reset()
❏ Now run the following command to draw a circle with radius 30.
circle(30)
❏ Run the following commands one at a time and watch what happens:
penup()
forward(100)
pendown()
circle(50)
❏ Draw a series of circles that get smaller from left to right. If you make a mistake, you can use reset() to clear the canvas.
So far you've been running one line of code at a time, which is a good way to learn the basics. The next step is to write several lines of code and run them all at once. To do that, you'll need to store your code in a .py file.
❏ In the toolbar, go to File > New File.
❏ A new text editor window will pop up. Type the lines below.
from turtle import *
shape('turtle')
forward(100)
❏ Go to Run > Run Module in the toolbar.
❏ You'll be prompted to save your file before running it. Click OK.
❏ Choose a filename and save your .py file somewhere memorable.
Once your file is saved, your turtle drawing will get started.
Note that there's some text output in the IDLE shell window where you were typing commands earlier. If you get an error, you can check this window for details.
❏ Add the line width(5) to your code to make your line thicker. Go to Run > Run Module in the toolbar or press F5 to run your code.
from turtle import *
shape('turtle')
width(5)
circle(200)
❏ Now add the line color('purple') to make the line purple. Go to Run > Run Module in the toolbar or press F5 to run your code.
from turtle import *
shape('turtle')
width(5)
color('purple')
circle(200)
❏ Next you'll fill in a shape with color. Start by adding the line fillcolor('pink') at the beginning of your code. You can swap in the name of a different color if you prefer.
❏ Next, add the lines begin_fill() and end_fill() at the beginning and end of drawing a shape. Go to Run > Run Module in the toolbar or press F5 to run your code.
from turtle import *
shape('turtle')
width(5)
color('purple')
fillcolor('pink')
begin_fill()
circle(200)
end_fill()
❏ To set the background color for the whole canvas, you can use the bgcolor() function.
bgcolor('orange')
You can use a for loop to run the same piece of code as many times as you want.
Here's what a for loop looks like in Python. The line for i in range(25): starts the loop, and the indented lines underneath will run repeatedly. You can indent using a tab or 4 spaces. The function range(25) specifies that the loop will run 25 times.
for i in range(25):
begin_fill()
circle(50-i)
end_fill()
The first time this loop runs, the variable i will have the value 0. The second time it runs, i will be 1, etc. On the final iteration, i will equal 24.
The code above draws a circle with 50-i (fifty minus i) as the radius value every time the for loop runs.
❏ The code below is an update on the previous for loop, starting with a radius of 150 and reducing it by i*5 on each iteration. (In Python, * is the multiplication symbol.)
for i in range(25):
begin_fill()
circle(150-(i*5))
end_fill()
❏ Use a for loop with penup() and pendown() to make a dotted line.
❏ Use a for loop to draw the same shape at a range of different angles.
❏ If you want to use random numbers in your Python Turtle code, you'll need to include the line import random near the beginning.
The method random.randint(1,360) will return a random integer from 1 to 360, inclusive. You can put the whole function between the parentheses of a left() or right() function to choose an angle at random.
The code below also uses the home() function to return the turtle to its original position without erasing the drawing.
from turtle import *
import random
width(3)
color('purple')
bgcolor('lightyellow')
for i in range(70):
penup()
home()
left(random.randint(1,360))
forward(random.randint(30,250))
pendown()
for j in range(4):
forward(30)
left(90)
If you want your turtle to draw faster, You can add the speed() function at the beginning of your program. The maximum speed is 9.
speed(9)
To hide your turtle cursor so you can get a clean screenshot, use the hideturtle() function.
hideturtle()
In the example below, we start by creating a list of color names and storing it as a variable called color_list. In addition to the color names we're using below, you can use hex-formatted colors such as #01d6ae.
Later in the code we use random.choice(color_list) to select a random color from the list, which is passed to the fillcolor() function to set the color of the current shape.
from turtle import *
import random
width(3)
color('purple')
bgcolor('lightyellow')
speed(9)
color_list = ['red','orange','yellow','lightgreen','lightblue','violet']
for i in range(70):
penup()
home()
left(random.randint(1,360))
forward(random.randint(30,250)
pendown()
fillcolor(random.choice(color_list))
begin_fill()
for j in range(4):
forward(30)
left(90)
end_fill()
hideturtle()
The code above uses a for loop to draw each square, starting with the line for j in range(4):. Note that this loop is inside another for loop, so the code inside it is double indented.
❏ Draw a house
❏ Draw a happy robot
❏ Draw a worm
❏ Draw a pentagon
❏ Draw an n-sided polygon
❏ Draw a 5-sided star
❏ Draw an n-sided star
❏ Draw a flower
❏ Draw a flower with n petals
❏ Write your name in cursive
❏ Draw a randomized night sky with shooting stars
❏ Draw a tree with random details
Ubuntu instructions
If you're using Ubuntu or a similar Debian-based Linux distro, run the following commands to install IDLE:
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install idle
If you're using an older version of Ubuntu, you may also need to install the tkinter Python package:
sudo apt-get install python3-tk
macOS instructions
On Mac, open a terminal window and run idle3 to see if IDLE is installed.
If it isn't available, go to https://brew.sh and follow the instructions to install Homebrew. Then run the following commands to install Python3 and Tkinter:
brew install python3
brew install tkinter
Run the command idle3 and you should be good to go.
Windows instructions
Coming soon!
Updated August 27, 2023
You can find the latest version of this zine at the following URL: https://github.com/iffybooks/draw-with-code
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