4.8 A Few More turtle Methods and Observations¶

Turtle methods can use negative angles or distances.¶

tess.forward(-100)will move tess backwards
tess.left(-30)turns her to the right
because there are 360 degrees in a circle, turning 30 to the left will leave you facing in the same direction as turning 330 to the right
- The on-screen animation will differ, though — you will be able to tell if tess is turning clockwise or counter-clockwise
- This suggests that we don’t need both a left and a right turn method
There is also a backward method: alex.backward(100)

A turtle’s pen can be picked up or put down¶

This allows us to move a turtle to a different place without drawing a line
The methods are up and down
- penup and pendown do the same thing.
Every turtle can have its own shape. The ones available “out of the box” are
- arrow
- blank
- circle
- classic
- square
- triangle
- turtle

alex.shape("turtle")

You can speed up or slow down the turtle’s animation speed¶

Speed settings can be set between 1 (slowest) to 10 (fastest)
0 turns off animation and immediately draws shape

alex.speed(10)

import turtle
wn = turtle.Screen()
wn.bgcolor("lightgreen")
tess = turtle.Turtle()
tess.color("blue")
tess.shape("turtle")

print(list(range(5, 60, 2)))
tess.up()                     # this is new
for size in range(5, 60, 2):    # start with size = 5 and grow by 2
    tess.stamp()                # leave an impression on the canvas
    tess.forward(size)          # move tess along
    tess.right(24)              # and turn her

wn.exitonclick()