17.3. Turtle Methods

Turtles can do more than go forward, turn left, and turn right. The table below lists the turtle methods. Methods are functions that are defined in a class. A class defines what all objects of the class know (the data each object keeps track of) and can do (the behaviors an object can execute). You can think of a class as like a classification (type of thing).

Name	Input	Description
backward	amount	Moves the turle backward by the specified amount
color	colorname	Sets the pen color for drawing. Use ‘red’, ‘black’, etc
forward	amount	Moves the turtle forward by the specified amount
goto	x,y	Moves the turtle to position x,y
left	angle	Turns the turtle counter clockwise by the specified angle
pendown	None	Puts down the turtles tail so that it draws when it moves
penup	None	Picks up the turtles tail so that it doesn’t draw when it moves
pensize	width	Sets the width of the pen for drawing
right	angle	Turns the turtle clockwise by the specified angle
setheading	angle	Turns the turtle to face the given heading. East is 0, north is 90, west is 180, and south is 270.
Turtle	None	Creates and returns a new turtle object

You can draw a block style C with a turtle. Can you draw more than one letter? You would have to use the penup() procedure to pick up the pen and then move to the new location to draw the second letter and then put the pen down using pendown() as shown in the example below.

Run the code to see what it draws.

from turtle import * # use the turtle library space = Screen() # create a turtle space ji = Turtle() # create a turtle named ji ji.right(180) # turn right by 180 degrees ji.forward(75) # move forward by 75 units ji.right(90) # turn right 90 degrees ji.forward(100) # more forward by 90 units ji.right(90) # turn right 90 degrees ji.forward(75) # move forward by 75 units ji.penup() # pick up the pen ji.forward(50) # move forward 50 units ji.pendown() # put the pen down ji.right(90) # turn right 90 degrees ji.forward(100) # go forward 100 units ji.left(90) # turn left 90 degrees ji.forward(75) # go forward 75 units

The space that the turtle draws in is 320 by 320 pixels. The center of the space is at x=0, y=0.

Figure 1: The coordinates for the drawing space. Note that the center is x = 0 and y = 0.

The program below uses the goto(x,y) to move to the top left corner before drawing a C.

Run the code to see what it draws.

from turtle import * # use the turtle library space = Screen() # create a turtle space anu = Turtle() # create a turtle named anu anu.penup() # pick up the pen (don't draw) anu.goto(-75,150) # go to a location anu.pendown() # put down the pen anu.right(180) # turn to face west anu.forward(75) # move forward by 75 units anu.left(90) # turn right 90 degrees anu.forward(100) # more forward by 90 units anu.left(90) # turn right 90 degrees anu.forward(75) # move forward by 75 units

Note

Remember to put the pen down again after you have picked it up if you want to draw a line!

Mixed up programs

The following program uses a turtle to draw a capital F as shown in the picture below, but the lines are mixed up. The program should do all necessary set-up: import the turtle module, get the screen/space to draw on, and create the turtle. It should draw the lines in the order shown by the numbers in the picture on the left. Drag the needed blocks of statements from the left column to the right column and put them in the right order. There may be extra blocks that are not needed in a correct solution. Then click on Check to see if you are right. You will be told if any of the lines are in the wrong order or are the wrong blocks.

        from turtle import *
space = Screen()
anu = Turtle()
---
anu.left(90)
anu.forward(100)
---
anu.right(90)
anu.forward(50)
---
anu.left(90)
anu.forward(50) #paired
---
anu.penup()
---
anu.penUp() #paired
---
anu.goto(0,60)
---
anu.goTo(0,60) #paired
---
anu.pendown()
---
anu.penDown() #paired
---
anu.forward(50)
        

The following program uses a turtle to draw a capital A as shown in the picture below, but the lines are mixed up. The program should do all necessary set-up: import the turtle module, get the screen/space to draw on, and create the turtle. It should draw the lines in the order shown by the numbers in the picture on the left. Drag the needed blocks of statements from the left column to the right column and put them in the right order. There may be additional blocks that are not needed in a correct solution. Then click on Check to see if you are right. You will be told if any of the lines are in the wrong order or are the wrong blocks.

        from turtle import *
---
space = Screen()
---
space = screen() #paired
---
ella = Turtle()
---
ella = Turtle #paired
---
ella.left(60)
ella.forward(100)
---
ella.left(60)
ella.forward() #paired
---
ella.right(120)
ella.forward(100)
---
ella.penup()
ella.goto(30,50)
ella.pendown()
---
ella.left(60)
ella.forward(40)
---
ella.Left(60)
ella.forward(40) #paired
        

You can change the color and pensize that you draw with as well.

Run the code to see what it draws.

from turtle import * # use the turtle library space = Screen() # create a turtle space anu = Turtle() # create a turtle named anu anu.color('red') # set the pen color to red anu.pensize(25) # set the size of the pen anu.right(180) # turn right by 180 degrees anu.forward(75) # move forward by 75 units anu.right(90) # turn right 90 degrees anu.color('blue') # set the pen color to blue anu.pensize(50) # set the pen size to 10 anu.forward(100) # move forward by 100 units

Use the area below to try to draw to draw your initials in block style with two different colors.

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