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Turtle Graphics with loops

Shapes
To start, let's try some basic designs without loops.  
Square
square.py
import turtle
turtle.showturtle()
turtle.shape("turtle")
turtle.forward(50)
turtle.right(90)
turtle.forward(50)
turtle.right(90)
turtle.forward(50)
turtle.right(90)
turtle.forward(50)
turtle.right(90)
To add color to your design, wrap the following lines of code before and after the turtle movements.
turtle.fillcolor("green")
turtle.begin_fill()
turtle.end_fill()
import turtle
turtle.showturtle()
turtle.shape("turtle")
turtle.fillcolor("green")
turtle.begin_fill()
turtle.forward(50)
turtle.right(90)
turtle.forward(50)
turtle.right(90)
turtle.forward(50)
turtle.right(90)
turtle.forward(50)
turtle.right(90)
turtle.end_fill()
turtle.pencolor("red") # this statement changes the pen's color.
Rectangle
Let's draw a rectangle using variables.  In Python, you name a variable and assign it a value.   Replace each length and angle with a variable.
rectangle.py
import turtle
turtle.showturtle()
turtle.shape("turtle")
length1 = 100
length2 = 200
angle = 90
turtle.forward(length1)
turtle.right(angle)
turtle.forward(length2)
turtle.right(angle)
turtle.forward(length1)
turtle.right(angle)
turtle.forward(length2)
turtle.right(angle)
​
Zigzag
Star
zigzag.py
import turtle
length = 25
angle = 45
turtle.showturtle()
turtle.shape("turtle")
turtle.forward(length)
turtle.right(angle)
turtle.forward(length)
turtle.left(angle)
turtle.forward(length)
turtle.right(angle)
turtle.forward(length)
turtle.left(angle)
turtle.forward(length)
turtle.right(angle)
turtle.forward(length)
turtle.left(angle)
turtle.forward(length)
turtle.right(angle)
turtle.forward(length)
Spiral
spiral.py
import turtle
length = 10
angle = 90
turtle.showturtle()
turtle.shape("turtle")
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
turtle.forward(length+length)
turtle.right(angle)
length = length + 10
Loops
Loops are used when you have a block of code that you want to repeat.   
A for loop is used when you have a block of code which you want to repeat a fixed number of times.   The for loop iterates through the block of indented code.
​
​
for x in range():
x is a variable that steps through values
     <do something>
do something in the indented block
for.py
for x in range(4):
    print(x)
$ python for.py
0
1
2
3
4
Square
square2.py
import turtle
turtle.showturtle()
turtle.shape("turtle")
for x in range(4):
    turtle.forward(50)
    turtle.right(90)
Spiral
spiral2.py
import turtle
length = 10
angle = 90
turtle.showturtle()
turtle.shape("turtle")
for x in range(10):
    turtle.forward(length+length)
    turtle.right(angle)
    length = length + 10
spiral3.py
import turtle
angle = 91
turtle.showturtle()
turtle.shape("turtle")
for x in range(100):
    turtle.forward(x)
    turtle.left(angle)
circle.py
import turtle
angle = 91
turtle.showturtle()
turtle.shape("turtle")
for x in range(100):
    turtle.circle(x)
    turtle.left(angle)
Polygons
Shape
Sides
Interior Angle
Triangle
3
60
Quadrilateral
4
90
Pentagon
5
108
Hexagon
6
120
Heptagon
7
128.571
Octagon
8
135
Nonagon
9
140
Decagon
10
144
Hendecagon
11
147.273
Dodecagon
12
150
triangle.py
import turtle
length = 100
angle = 120
turtle.showturtle()
turtle.shape("turtle")
for i in range(3):
    turtle.forward(length)
    turtle.right(angle)
Star
Using a loop, we can produce an eight point star.
star1.py
import turtle
turtle.showturtle()
turtle.shape("turtle")
turtle.pencolor('green')
for x in range(13):
        turtle.forward(200)
        turtle.left(150)
What happens if we try changing the range and the left angle?
star2.py
import turtle
turtle.showturtle()
turtle.shape("turtle")
turtle.pencolor('purple')
for x in range(100):
        turtle.forward(200)
        turtle.left(175)
Spiral Circle
spiral.py
import turtle
turtle.showturtle()
turtle.shape("turtle")
turtle.pencolor('pink')
for i in range(180):
    turtle.forward(100)
    turtle.right(30)
    turtle.forward(20)
    turtle.left(60)
    turtle.forward(50)
    turtle.right(30)
    turtle.penup()
    turtle.setposition(0, 0)
    turtle.pendown()
    turtle.right(2)

Turtle Maze Problems

Turtle Snake

Last modified 4yr ago


for x in range():	x is a variable that steps through values
<do something>	do something in the indented block

Shape	Sides	Interior Angle
Triangle	3	60
Quadrilateral	4	90
Pentagon	5	108
Hexagon	6	120
Heptagon	7	128.571
Octagon	8	135
Nonagon	9	140
Decagon	10	144
Hendecagon	11	147.273
Dodecagon	12	150