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Introduction

Python Turtle

  • Python is a highly popular programming language, used by many large organisations.
  • Facebook, NASA, IBM, Google and Yahoo among others all use it extensively.
  • It is considered by many to be one of the easiest languages to pick up.
  • One of the big attractions of Python is that many 'libraries' are available to provide it with extra functionality.
  • A library is a set of extra functions that help perform different types of task. There are libraries for advanced maths, graph drawing, graphics, game writing, random numbers and so forth.
  • We're going to use a fun library called 'Turtle', which allows for the convenient drawing of lines and shapes.

Let's get started

  • Load up the Python Development, called IDLE.
  • You'll be presented with the Python Shell window, which looks like this…

shell.png

  • With the mouse in the shell window, type the following at the >>> Prompt.
  • Hit enter after each line.
  • (Note: Make sure you write Screen with a capital letter!
import turtle
wn=turtle.Screen()
wn.bgcolor("lightgreen")
wn.title("Turtle Power")
  • A graphics window (currently empty) will appear that we can draw into.
  • We've called our screen object, "wn". Every time we want Python to control somthing to do with this window, we'll need to put wn. in front of the command.
  • We also changed the background colour, and put a title on the window.
  • Let's add a "turtle" to the screen. We can move this arounnd the screen to draw shapes and patterns. We'll call our turtle, "Tess".
tess=turtle.Turtle()
tess.color("hotpink")
tess.pensize(5)
tess.shape("turtle")
  • When we created a tess object, we then went on to set some of her properties - colour, thickness of the lines she'll draw and how she appears on the screen.
  • Incidentally, a full colour list can be found here.
  • We could add other turtle objects too, if we wanted, and have several drawing shapes on the screen. We might have a look at that later on.
  • Next, lets start to draw. Type…
tess.forward(100)
tess.left(90)
tess.forward(100)
tess.left(90)
tess.forward(100)
tess.left(90)
tess.forward(100)
tess.left(90)
  • Your turtle should have traced a square shape for you.

Your turn

Try it

  • Tip: You can move the turtle back to the centre, and clear the screen at any time by using the commands…
tess.home()
tess.clear()
  • Experiment with drawing lines until you're confident, then try the badge task.

Badge it

  • Silver: Draw a red triangle, (screenshot the result, and upload the image file to BourneToLearn)
  • Gold: Draw a pentagon, where each side is a different colour,
  • Platinum: Create second turtle on the screen, and call it tom. Have this draw a black square, and the other turtle draw a green square, so that they look like this…

squares.png

Write interpreter commands to draw a grid two squares tall and two squares wide (like the Windows logo). Each square should be a different colour.

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