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Start from a working program: cheat sheet

Python functions and events · In any playground, open Reference to copy these.

forward

Move the turtle forward. The number is how many steps.

forward(100)
What it draws

right

Turn clockwise by this many degrees.

right(90)
Example
forward(60)
right(90)
forward(60)
What it draws

goto

Jump to a position. (0, 0) is the centre; x goes right, y goes up.

goto(0, 0)
Example
goto(80, 60)
What it draws
From the centre to (80, 60)

pendown

Put the pen down so moving draws again.

pendown()
Example
forward(40)
penup()
forward(40)
pendown()
forward(40)
What it draws
Pen down again for the last part

pencolor

Set the line colour, using a colour name.

pencolor("red")
Example
pencolor("red")
forward(100)
What it draws

begin_fill / end_fill

Everything drawn between these two lines is filled in.

begin_fill()

end_fill()
Example
fillcolor("orange")
begin_fill()
for i in range(4):
    forward(60)
    right(90)
end_fill()
What it draws

square (loop)

Draw a square by repeating forward and right four times.

for i in range(4):
    forward(100)
    right(90)
What it draws

if / else

Do one thing or the other, depending on a condition.

if x > 0:
    pass
else:
    pass
Example
for x in [-90, -30, 30, 90]:
    penup()
    goto(x, 0)
    if x > 0:
        dot(30, "red")
    else:
        dot(30, "blue")
hideturtle()
What it draws
Red when x > 0, else blue

variable

Give a value a name, so you can reuse and change it.

size = 50
Example
length = 120
forward(length)
left(90)
forward(length / 2)
What it draws
length = 120, then half of it

grow value

Change a value every pass: read the old one, store a new one.

size = 5
for i in range(20):
    forward(size)
    right(90)
    size = size + 5
Example
size = 5
for i in range(30):
    forward(size)
    right(90)
    size = size + 5
What it draws
The same spiral, grown by an update

backward

Move the turtle backward without turning.

backward(100)
What it draws

left

Turn anticlockwise by this many degrees.

left(90)
Example
forward(60)
left(90)
forward(60)
What it draws

penup

Lift the pen so moving does not draw.

penup()
Example
forward(40)
penup()
forward(40)
pendown()
forward(40)
What it draws
Pen up for the middle part

pensize

Set how thick the line is.

pensize(5)
Example
pensize(1)
forward(50)
pensize(8)
forward(50)
What it draws
pensize(1), then pensize(8)

fillcolor

Choose the colour to fill shapes with.

fillcolor("blue")
Example
fillcolor("blue")
begin_fill()
circle(40)
end_fill()
What it draws

speed

How fast the turtle moves, from 1 (slow) to 10 (fast).

speed(10)

circle

Draw a circle with this radius.

circle(50)
What it draws
circle(50) starts at the turtle and curves left

for loop

Repeat the indented lines this many times.

for i in range(4):
    pass
Example
for i in range(5):
    forward(15)
    penup()
    forward(10)
    pendown()
What it draws
range(5): five dashes

every other

i % 2 == 0 is true on every second pass.

for i in range(8):
    if i % 2 == 0:
        pass
    else:
        pass
Example
for i in range(8):
    if i % 2 == 0:
        pencolor("red")
    else:
        pencolor("blue")
    pensize(6)
    forward(30)
    right(45)
What it draws
Red and blue sides, taking turns

counter step

Use the counter i to make each pass different.

for i in range(20):
    forward(i * 5)
    right(90)
Example
for i in range(30):
    forward(i * 5)
    right(90)
What it draws
A square spiral: each line longer than the last

list

Keep many values in order under one name. The first item is place 0.

colours = ["red", "blue", "green"]