turtle — Turtle graphics (original) (raw)

Source code: Lib/turtle.py

Introduction

Turtle graphics is an implementation of the popular geometric drawing tools introduced in Logo, developed by Wally Feurzeig, Seymour Papert and Cynthia Solomon in 1967.

Get started

Imagine a robotic turtle starting at (0, 0) in the x-y plane. After an import turtle, give it the command turtle.forward(15), and it moves (on-screen!) 15 pixels in the direction it is facing, drawing a line as it moves. Give it the commandturtle.right(25), and it rotates in-place 25 degrees clockwise.

In Python, turtle graphics provides a representation of a physical “turtle” (a little robot with a pen) that draws on a sheet of paper on the floor.

It’s an effective and well-proven way for learners to encounter programming concepts and interaction with software, as it provides instant, visible feedback. It also provides convenient access to graphical output in general.

Turtle drawing was originally created as an educational tool, to be used by teachers in the classroom. For the programmer who needs to produce some graphical output it can be a way to do that without the overhead of introducing more complex or external libraries into their work.

Tutorial

New users should start here. In this tutorial we’ll explore some of the basics of turtle drawing.

Starting a turtle environment

In a Python shell, import all the objects of the turtle module:

If you run into a No module named '_tkinter' error, you’ll have to install the Tk interface package on your system.

Basic drawing

Send the turtle forward 100 steps:

You should see (most likely, in a new window on your display) a line drawn by the turtle, heading East. Change the direction of the turtle, so that it turns 120 degrees left (anti-clockwise):

Let’s continue by drawing a triangle:

forward(100) left(120) forward(100)

Notice how the turtle, represented by an arrow, points in different directions as you steer it.

Experiment with those commands, and also with backward() andright().

Pen control

Try changing the color - for example, color('blue') - and width of the line - for example, width(3) - and then drawing again.

You can also move the turtle around without drawing, by lifting up the pen:up() before moving. To start drawing again, use down().

The turtle’s position

Send your turtle back to its starting-point (useful if it has disappeared off-screen):

The home position is at the center of the turtle’s screen. If you ever need to know them, get the turtle’s x-y coordinates with:

Home is at (0, 0).

And after a while, it will probably help to clear the window so we can start anew:

Making algorithmic patterns

Using loops, it’s possible to build up geometric patterns:

for steps in range(100): for c in ('blue', 'red', 'green'): color(c) forward(steps) right(30)

- which of course, are limited only by the imagination!

Let’s draw the star shape at the top of this page. We want red lines, filled in with yellow:

color('red') fillcolor('yellow')

Just as up() and down() determine whether lines will be drawn, filling can be turned on and off:

Next we’ll create a loop:

while True: forward(200) left(170) if abs(pos()) < 1: break

abs(pos()) < 1 is a good way to know when the turtle is back at its home position.

Finally, complete the filling:

(Note that filling only actually takes place when you give theend_fill() command.)

How to…

This section covers some typical turtle use-cases and approaches.

Get started as quickly as possible

One of the joys of turtle graphics is the immediate, visual feedback that’s available from simple commands - it’s an excellent way to introduce children to programming ideas, with a minimum of overhead (not just children, of course).

The turtle module makes this possible by exposing all its basic functionality as functions, available with from turtle import *. The turtle graphics tutorial covers this approach.

It’s worth noting that many of the turtle commands also have even more terse equivalents, such as fd() for forward(). These are especially useful when working with learners for whom typing is not a skill.

You’ll need to have the Tk interface package installed on your system for turtle graphics to work. Be warned that this is not always straightforward, so check this in advance if you’re planning to use turtle graphics with a learner.

Use the turtle module namespace

Using from turtle import * is convenient - but be warned that it imports a rather large collection of objects, and if you’re doing anything but turtle graphics you run the risk of a name conflict (this becomes even more an issue if you’re using turtle graphics in a script where other modules might be imported).

The solution is to use import turtle - fd() becomesturtle.fd(), width() becomes turtle.width() and so on. (If typing “turtle” over and over again becomes tedious, use for example import turtle as t instead.)

Use turtle graphics in a script

It’s recommended to use the turtle module namespace as described immediately above, for example:

import turtle as t from random import random

for i in range(100): steps = int(random() * 100) angle = int(random() * 360) t.right(angle) t.fd(steps)

Another step is also required though - as soon as the script ends, Python will also close the turtle’s window. Add:

to the end of the script. The script will now wait to be dismissed and will not exit until it is terminated, for example by closing the turtle graphics window.

Use object-oriented turtle graphics

Other than for very basic introductory purposes, or for trying things out as quickly as possible, it’s more usual and much more powerful to use the object-oriented approach to turtle graphics. For example, this allows multiple turtles on screen at once.

In this approach, the various turtle commands are methods of objects (mostly ofTurtle objects). You can use the object-oriented approach in the shell, but it would be more typical in a Python script.

The example above then becomes:

from turtle import Turtle from random import random

t = Turtle() for i in range(100): steps = int(random() * 100) angle = int(random() * 360) t.right(angle) t.fd(steps)

t.screen.mainloop()

Note the last line. t.screen is an instance of the Screenthat a Turtle instance exists on; it’s created automatically along with the turtle.

The turtle’s screen can be customised, for example:

t.screen.title('Object-oriented turtle demo') t.screen.bgcolor("orange")

Turtle graphics reference

Note

In the following documentation the argument list for functions is given. Methods, of course, have the additional first argument self which is omitted here.

Turtle methods

Turtle motion

Move and draw

Tell Turtle’s state

Setting and measurement

Pen control

Drawing state

Color control

Filling

More drawing control

Turtle state

Visibility

Appearance

Using events

Special Turtle methods

Methods of TurtleScreen/Screen

Window control

Animation control

Using screen events

Settings and special methods

Input methods

Methods specific to Screen

Methods of RawTurtle/Turtle and corresponding functions

Most of the examples in this section refer to a Turtle instance calledturtle.

Turtle motion

turtle.forward(distance)

turtle.fd(distance)

Parameters:

distance – a number (integer or float)

Move the turtle forward by the specified distance, in the direction the turtle is headed.

turtle.position() (0.00,0.00) turtle.forward(25) turtle.position() (25.00,0.00) turtle.forward(-75) turtle.position() (-50.00,0.00)

turtle.back(distance)

turtle.bk(distance)

turtle.backward(distance)

Parameters:

distance – a number

Move the turtle backward by distance, opposite to the direction the turtle is headed. Do not change the turtle’s heading.

turtle.position() (0.00,0.00) turtle.backward(30) turtle.position() (-30.00,0.00)

turtle.right(angle)

turtle.rt(angle)

Parameters:

angle – a number (integer or float)

Turn turtle right by angle units. (Units are by default degrees, but can be set via the degrees() and radians() functions.) Angle orientation depends on the turtle mode, see mode().

turtle.heading() 22.0 turtle.right(45) turtle.heading() 337.0

turtle.left(angle)

turtle.lt(angle)

Parameters:

angle – a number (integer or float)

Turn turtle left by angle units. (Units are by default degrees, but can be set via the degrees() and radians() functions.) Angle orientation depends on the turtle mode, see mode().

turtle.heading() 22.0 turtle.left(45) turtle.heading() 67.0

turtle.goto(x, y=None)

turtle.setpos(x, y=None)

turtle.setposition(x, y=None)

Parameters:

If y is None, x must be a pair of coordinates or a Vec2D(e.g. as returned by pos()).

Move turtle to an absolute position. If the pen is down, draw line. Do not change the turtle’s orientation.

tp = turtle.pos() tp (0.00,0.00) turtle.setpos(60,30) turtle.pos() (60.00,30.00) turtle.setpos((20,80)) turtle.pos() (20.00,80.00) turtle.setpos(tp) turtle.pos() (0.00,0.00)

turtle.teleport(x, y=None, *, fill_gap=False)

Parameters:

Move turtle to an absolute position. Unlike goto(x, y), a line will not be drawn. The turtle’s orientation does not change. If currently filling, the polygon(s) teleported from will be filled after leaving, and filling will begin again after teleporting. This can be disabled with fill_gap=True, which makes the imaginary line traveled during teleporting act as a fill barrier like in goto(x, y).

tp = turtle.pos() tp (0.00,0.00) turtle.teleport(60) turtle.pos() (60.00,0.00) turtle.teleport(y=10) turtle.pos() (60.00,10.00) turtle.teleport(20, 30) turtle.pos() (20.00,30.00)

Added in version 3.12.

turtle.setx(x)

Parameters:

x – a number (integer or float)

Set the turtle’s first coordinate to x, leave second coordinate unchanged.

turtle.position() (0.00,240.00) turtle.setx(10) turtle.position() (10.00,240.00)

turtle.sety(y)

Parameters:

y – a number (integer or float)

Set the turtle’s second coordinate to y, leave first coordinate unchanged.

turtle.position() (0.00,40.00) turtle.sety(-10) turtle.position() (0.00,-10.00)

turtle.setheading(to_angle)

turtle.seth(to_angle)

Parameters:

to_angle – a number (integer or float)

Set the orientation of the turtle to to_angle. Here are some common directions in degrees:

standard mode logo mode
0 - east 0 - north
90 - north 90 - east
180 - west 180 - south
270 - south 270 - west

turtle.setheading(90) turtle.heading() 90.0

turtle.home()

Move turtle to the origin – coordinates (0,0) – and set its heading to its start-orientation (which depends on the mode, see mode()).

turtle.heading() 90.0 turtle.position() (0.00,-10.00) turtle.home() turtle.position() (0.00,0.00) turtle.heading() 0.0

turtle.circle(radius, extent=None, steps=None)

Parameters:

Draw a circle with given radius. The center is radius units left of the turtle; extent – an angle – determines which part of the circle is drawn. If extent is not given, draw the entire circle. If _extent_is not a full circle, one endpoint of the arc is the current pen position. Draw the arc in counterclockwise direction if radius is positive, otherwise in clockwise direction. Finally the direction of the turtle is changed by the amount of extent.

As the circle is approximated by an inscribed regular polygon, _steps_determines the number of steps to use. If not given, it will be calculated automatically. May be used to draw regular polygons.

turtle.home() turtle.position() (0.00,0.00) turtle.heading() 0.0 turtle.circle(50) turtle.position() (-0.00,0.00) turtle.heading() 0.0 turtle.circle(120, 180) # draw a semicircle turtle.position() (0.00,240.00) turtle.heading() 180.0

turtle.dot(size=None, *color)

Parameters:

Draw a circular dot with diameter size, using color. If size is not given, the maximum of pensize+4 and 2*pensize is used.

turtle.home() turtle.dot() turtle.fd(50); turtle.dot(20, "blue"); turtle.fd(50) turtle.position() (100.00,-0.00) turtle.heading() 0.0

turtle.stamp()

Stamp a copy of the turtle shape onto the canvas at the current turtle position. Return a stamp_id for that stamp, which can be used to delete it by calling clearstamp(stamp_id).

turtle.color("blue") stamp_id = turtle.stamp() turtle.fd(50)

turtle.clearstamp(stampid)

Parameters:

stampid – an integer, must be return value of previousstamp() call

Delete stamp with given stampid.

turtle.position() (150.00,-0.00) turtle.color("blue") astamp = turtle.stamp() turtle.fd(50) turtle.position() (200.00,-0.00) turtle.clearstamp(astamp) turtle.position() (200.00,-0.00)

turtle.clearstamps(n=None)

Parameters:

n – an integer (or None)

Delete all or first/last n of turtle’s stamps. If n is None, delete all stamps, if n > 0 delete first n stamps, else if n < 0 delete last n stamps.

for i in range(8): ... unused_stamp_id = turtle.stamp() ... turtle.fd(30) turtle.clearstamps(2) turtle.clearstamps(-2) turtle.clearstamps()

turtle.undo()

Undo (repeatedly) the last turtle action(s). Number of available undo actions is determined by the size of the undobuffer.

for i in range(4): ... turtle.fd(50); turtle.lt(80) ... for i in range(8): ... turtle.undo()

turtle.speed(speed=None)

Parameters:

speed – an integer in the range 0..10 or a speedstring (see below)

Set the turtle’s speed to an integer value in the range 0..10. If no argument is given, return current speed.

If input is a number greater than 10 or smaller than 0.5, speed is set to 0. Speedstrings are mapped to speedvalues as follows:

Speeds from 1 to 10 enforce increasingly faster animation of line drawing and turtle turning.

Attention: speed = 0 means that no animation takes place. forward/back makes turtle jump and likewise left/right make the turtle turn instantly.

turtle.speed() 3 turtle.speed('normal') turtle.speed() 6 turtle.speed(9) turtle.speed() 9

Tell Turtle’s state

turtle.position()

turtle.pos()

Return the turtle’s current location (x,y) (as a Vec2D vector).

turtle.pos() (440.00,-0.00)

turtle.towards(x, y=None)

Parameters:

Return the angle between the line from turtle position to position specified by (x,y), the vector or the other turtle. This depends on the turtle’s start orientation which depends on the mode - “standard”/”world” or “logo”.

turtle.goto(10, 10) turtle.towards(0,0) 225.0

turtle.xcor()

Return the turtle’s x coordinate.

turtle.home() turtle.left(50) turtle.forward(100) turtle.pos() (64.28,76.60) print(round(turtle.xcor(), 5)) 64.27876

turtle.ycor()

Return the turtle’s y coordinate.

turtle.home() turtle.left(60) turtle.forward(100) print(turtle.pos()) (50.00,86.60) print(round(turtle.ycor(), 5)) 86.60254

turtle.heading()

Return the turtle’s current heading (value depends on the turtle mode, seemode()).

turtle.home() turtle.left(67) turtle.heading() 67.0

turtle.distance(x, y=None)

Parameters:

Return the distance from the turtle to (x,y), the given vector, or the given other turtle, in turtle step units.

turtle.home() turtle.distance(30,40) 50.0 turtle.distance((30,40)) 50.0 joe = Turtle() joe.forward(77) turtle.distance(joe) 77.0

Settings for measurement

turtle.degrees(fullcircle=360.0)

Parameters:

fullcircle – a number

Set angle measurement units, i.e. set number of “degrees” for a full circle. Default value is 360 degrees.

turtle.home() turtle.left(90) turtle.heading() 90.0

Change angle measurement unit to grad (also known as gon, grade, or gradian and equals 1/100-th of the right angle.)

turtle.degrees(400.0) turtle.heading() 100.0 turtle.degrees(360) turtle.heading() 90.0

turtle.radians()

Set the angle measurement units to radians. Equivalent todegrees(2*math.pi).

turtle.home() turtle.left(90) turtle.heading() 90.0 turtle.radians() turtle.heading() 1.5707963267948966

Pen control

Drawing state

turtle.pendown()

turtle.pd()

turtle.down()

Pull the pen down – drawing when moving.

turtle.penup()

turtle.pu()

turtle.up()

Pull the pen up – no drawing when moving.

turtle.pensize(width=None)

turtle.width(width=None)

Parameters:

width – a positive number

Set the line thickness to width or return it. If resizemode is set to “auto” and turtleshape is a polygon, that polygon is drawn with the same line thickness. If no argument is given, the current pensize is returned.

turtle.pensize() 1 turtle.pensize(10) # from here on lines of width 10 are drawn

turtle.pen(pen=None, **pendict)

Parameters:

Return or set the pen’s attributes in a “pen-dictionary” with the following key/value pairs:

This dictionary can be used as argument for a subsequent call to pen()to restore the former pen-state. Moreover one or more of these attributes can be provided as keyword-arguments. This can be used to set several pen attributes in one statement.

turtle.pen(fillcolor="black", pencolor="red", pensize=10) sorted(turtle.pen().items()) [('fillcolor', 'black'), ('outline', 1), ('pencolor', 'red'), ('pendown', True), ('pensize', 10), ('resizemode', 'noresize'), ('shearfactor', 0.0), ('shown', True), ('speed', 9), ('stretchfactor', (1.0, 1.0)), ('tilt', 0.0)] penstate=turtle.pen() turtle.color("yellow", "") turtle.penup() sorted(turtle.pen().items())[:3] [('fillcolor', ''), ('outline', 1), ('pencolor', 'yellow')] turtle.pen(penstate, fillcolor="green") sorted(turtle.pen().items())[:3] [('fillcolor', 'green'), ('outline', 1), ('pencolor', 'red')]

turtle.isdown()

Return True if pen is down, False if it’s up.

turtle.penup() turtle.isdown() False turtle.pendown() turtle.isdown() True

Color control

turtle.pencolor(*args)

Return or set the pencolor.

Four input formats are allowed:

pencolor()

Return the current pencolor as color specification string or as a tuple (see example). May be used as input to another color/pencolor/fillcolor call.

pencolor(colorstring)

Set pencolor to colorstring, which is a Tk color specification string, such as "red", "yellow", or "#33cc8c".

pencolor((r, g, b))

Set pencolor to the RGB color represented by the tuple of r, g, and_b_. Each of r, g, and b must be in the range 0..colormode, where colormode is either 1.0 or 255 (see colormode()).

pencolor(r, g, b)

Set pencolor to the RGB color represented by r, g, and b. Each of_r_, g, and b must be in the range 0..colormode.

If turtleshape is a polygon, the outline of that polygon is drawn with the newly set pencolor.

colormode() 1.0 turtle.pencolor() 'red' turtle.pencolor("brown") turtle.pencolor() 'brown' tup = (0.2, 0.8, 0.55) turtle.pencolor(tup) turtle.pencolor() (0.2, 0.8, 0.5490196078431373) colormode(255) turtle.pencolor() (51.0, 204.0, 140.0) turtle.pencolor('#32c18f') turtle.pencolor() (50.0, 193.0, 143.0)

turtle.fillcolor(*args)

Return or set the fillcolor.

Four input formats are allowed:

fillcolor()

Return the current fillcolor as color specification string, possibly in tuple format (see example). May be used as input to another color/pencolor/fillcolor call.

fillcolor(colorstring)

Set fillcolor to colorstring, which is a Tk color specification string, such as "red", "yellow", or "#33cc8c".

fillcolor((r, g, b))

Set fillcolor to the RGB color represented by the tuple of r, g, and_b_. Each of r, g, and b must be in the range 0..colormode, where colormode is either 1.0 or 255 (see colormode()).

fillcolor(r, g, b)

Set fillcolor to the RGB color represented by r, g, and b. Each of_r_, g, and b must be in the range 0..colormode.

If turtleshape is a polygon, the interior of that polygon is drawn with the newly set fillcolor.

turtle.fillcolor("violet") turtle.fillcolor() 'violet' turtle.pencolor() (50.0, 193.0, 143.0) turtle.fillcolor((50, 193, 143)) # Integers, not floats turtle.fillcolor() (50.0, 193.0, 143.0) turtle.fillcolor('#ffffff') turtle.fillcolor() (255.0, 255.0, 255.0)

turtle.color(*args)

Return or set pencolor and fillcolor.

Several input formats are allowed. They use 0 to 3 arguments as follows:

color()

Return the current pencolor and the current fillcolor as a pair of color specification strings or tuples as returned by pencolor() andfillcolor().

color(colorstring), color((r,g,b)), color(r,g,b)

Inputs as in pencolor(), set both, fillcolor and pencolor, to the given value.

color(colorstring1, colorstring2), color((r1,g1,b1), (r2,g2,b2))

Equivalent to pencolor(colorstring1) and fillcolor(colorstring2)and analogously if the other input format is used.

If turtleshape is a polygon, outline and interior of that polygon is drawn with the newly set colors.

turtle.color("red", "green") turtle.color() ('red', 'green') color("#285078", "#a0c8f0") color() ((40.0, 80.0, 120.0), (160.0, 200.0, 240.0))

See also: Screen method colormode().

Filling

turtle.filling()

Return fillstate (True if filling, False else).

turtle.begin_fill() if turtle.filling(): ... turtle.pensize(5) ... else: ... turtle.pensize(3)

turtle.begin_fill()

To be called just before drawing a shape to be filled.

turtle.end_fill()

Fill the shape drawn after the last call to begin_fill().

Whether or not overlap regions for self-intersecting polygons or multiple shapes are filled depends on the operating system graphics, type of overlap, and number of overlaps. For example, the Turtle star above may be either all yellow or have some white regions.

turtle.color("black", "red") turtle.begin_fill() turtle.circle(80) turtle.end_fill()

More drawing control

turtle.reset()

Delete the turtle’s drawings from the screen, re-center the turtle and set variables to the default values.

turtle.goto(0,-22) turtle.left(100) turtle.position() (0.00,-22.00) turtle.heading() 100.0 turtle.reset() turtle.position() (0.00,0.00) turtle.heading() 0.0

turtle.clear()

Delete the turtle’s drawings from the screen. Do not move turtle. State and position of the turtle as well as drawings of other turtles are not affected.

turtle.write(arg, move=False, align='left', font=('Arial', 8, 'normal'))

Parameters:

Write text - the string representation of arg - at the current turtle position according to align (“left”, “center” or “right”) and with the given font. If move is true, the pen is moved to the bottom-right corner of the text. By default, move is False.

turtle.write("Home = ", True, align="center") turtle.write((0,0), True)

Turtle state

Visibility

turtle.hideturtle()

turtle.ht()

Make the turtle invisible. It’s a good idea to do this while you’re in the middle of doing some complex drawing, because hiding the turtle speeds up the drawing observably.

turtle.showturtle()

turtle.st()

Make the turtle visible.

turtle.isvisible()

Return True if the Turtle is shown, False if it’s hidden.

turtle.hideturtle() turtle.isvisible() False turtle.showturtle() turtle.isvisible() True

Appearance

turtle.shape(name=None)

Parameters:

name – a string which is a valid shapename

Set turtle shape to shape with given name or, if name is not given, return name of current shape. Shape with name must exist in the TurtleScreen’s shape dictionary. Initially there are the following polygon shapes: “arrow”, “turtle”, “circle”, “square”, “triangle”, “classic”. To learn about how to deal with shapes see Screen method register_shape().

turtle.shape() 'classic' turtle.shape("turtle") turtle.shape() 'turtle'

turtle.resizemode(rmode=None)

Parameters:

rmode – one of the strings “auto”, “user”, “noresize”

Set resizemode to one of the values: “auto”, “user”, “noresize”. If _rmode_is not given, return current resizemode. Different resizemodes have the following effects:

resizemode("user") is called by shapesize() when used with arguments.

turtle.resizemode() 'noresize' turtle.resizemode("auto") turtle.resizemode() 'auto'

turtle.shapesize(stretch_wid=None, stretch_len=None, outline=None)

turtle.turtlesize(stretch_wid=None, stretch_len=None, outline=None)

Parameters:

Return or set the pen’s attributes x/y-stretchfactors and/or outline. Set resizemode to “user”. If and only if resizemode is set to “user”, the turtle will be displayed stretched according to its stretchfactors: stretch_wid is stretchfactor perpendicular to its orientation, stretch_len is stretchfactor in direction of its orientation, outline determines the width of the shape’s outline.

turtle.shapesize() (1.0, 1.0, 1) turtle.resizemode("user") turtle.shapesize(5, 5, 12) turtle.shapesize() (5, 5, 12) turtle.shapesize(outline=8) turtle.shapesize() (5, 5, 8)

turtle.shearfactor(shear=None)

Parameters:

shear – number (optional)

Set or return the current shearfactor. Shear the turtleshape according to the given shearfactor shear, which is the tangent of the shear angle. Do not change the turtle’s heading (direction of movement). If shear is not given: return the current shearfactor, i. e. the tangent of the shear angle, by which lines parallel to the heading of the turtle are sheared.

turtle.shape("circle") turtle.shapesize(5,2) turtle.shearfactor(0.5) turtle.shearfactor() 0.5

turtle.tilt(angle)

Parameters:

angle – a number

Rotate the turtleshape by angle from its current tilt-angle, but do _not_change the turtle’s heading (direction of movement).

turtle.reset() turtle.shape("circle") turtle.shapesize(5,2) turtle.tilt(30) turtle.fd(50) turtle.tilt(30) turtle.fd(50)

turtle.tiltangle(angle=None)

Parameters:

angle – a number (optional)

Set or return the current tilt-angle. If angle is given, rotate the turtleshape to point in the direction specified by angle, regardless of its current tilt-angle. Do not change the turtle’s heading (direction of movement). If angle is not given: return the current tilt-angle, i. e. the angle between the orientation of the turtleshape and the heading of the turtle (its direction of movement).

turtle.reset() turtle.shape("circle") turtle.shapesize(5,2) turtle.tilt(45) turtle.tiltangle() 45.0

turtle.shapetransform(t11=None, t12=None, t21=None, t22=None)

Parameters:

Set or return the current transformation matrix of the turtle shape.

If none of the matrix elements are given, return the transformation matrix as a tuple of 4 elements. Otherwise set the given elements and transform the turtleshape according to the matrix consisting of first row t11, t12 and second row t21, t22. The determinant t11 * t22 - t12 * t21 must not be zero, otherwise an error is raised. Modify stretchfactor, shearfactor and tiltangle according to the given matrix.

turtle = Turtle() turtle.shape("square") turtle.shapesize(4,2) turtle.shearfactor(-0.5) turtle.shapetransform() (4.0, -1.0, -0.0, 2.0)

turtle.get_shapepoly()

Return the current shape polygon as tuple of coordinate pairs. This can be used to define a new shape or components of a compound shape.

turtle.shape("square") turtle.shapetransform(4, -1, 0, 2) turtle.get_shapepoly() ((50, -20), (30, 20), (-50, 20), (-30, -20))

Using events

turtle.onclick(fun, btn=1, add=None)

Parameters:

Bind fun to mouse-click events on this turtle. If fun is None, existing bindings are removed. Example for the anonymous turtle, i.e. the procedural way:

def turn(x, y): ... left(180) ... onclick(turn) # Now clicking into the turtle will turn it. onclick(None) # event-binding will be removed

turtle.onrelease(fun, btn=1, add=None)

Parameters:

Bind fun to mouse-button-release events on this turtle. If fun isNone, existing bindings are removed.

class MyTurtle(Turtle): ... def glow(self,x,y): ... self.fillcolor("red") ... def unglow(self,x,y): ... self.fillcolor("") ... turtle = MyTurtle() turtle.onclick(turtle.glow) # clicking on turtle turns fillcolor red, turtle.onrelease(turtle.unglow) # releasing turns it to transparent.

turtle.ondrag(fun, btn=1, add=None)

Parameters:

Bind fun to mouse-move events on this turtle. If fun is None, existing bindings are removed.

Remark: Every sequence of mouse-move-events on a turtle is preceded by a mouse-click event on that turtle.

turtle.ondrag(turtle.goto)

Subsequently, clicking and dragging the Turtle will move it across the screen thereby producing handdrawings (if pen is down).

Special Turtle methods

turtle.begin_poly()

Start recording the vertices of a polygon. Current turtle position is first vertex of polygon.

turtle.end_poly()

Stop recording the vertices of a polygon. Current turtle position is last vertex of polygon. This will be connected with the first vertex.

turtle.get_poly()

Return the last recorded polygon.

turtle.home() turtle.begin_poly() turtle.fd(100) turtle.left(20) turtle.fd(30) turtle.left(60) turtle.fd(50) turtle.end_poly() p = turtle.get_poly() register_shape("myFavouriteShape", p)

turtle.clone()

Create and return a clone of the turtle with same position, heading and turtle properties.

mick = Turtle() joe = mick.clone()

turtle.getturtle()

turtle.getpen()

Return the Turtle object itself. Only reasonable use: as a function to return the “anonymous turtle”:

pet = getturtle() pet.fd(50) pet <turtle.Turtle object at 0x...>

turtle.getscreen()

Return the TurtleScreen object the turtle is drawing on. TurtleScreen methods can then be called for that object.

ts = turtle.getscreen() ts <turtle._Screen object at 0x...> ts.bgcolor("pink")

turtle.setundobuffer(size)

Parameters:

size – an integer or None

Set or disable undobuffer. If size is an integer, an empty undobuffer of given size is installed. size gives the maximum number of turtle actions that can be undone by the undo() method/function. If size isNone, the undobuffer is disabled.

turtle.setundobuffer(42)

turtle.undobufferentries()

Return number of entries in the undobuffer.

while undobufferentries(): ... undo()

Compound shapes

To use compound turtle shapes, which consist of several polygons of different color, you must use the helper class Shape explicitly as described below:

  1. Create an empty Shape object of type “compound”.
  2. Add as many components to this object as desired, using theaddcomponent() method.
    For example:

    s = Shape("compound")
    poly1 = ((0,0),(10,-5),(0,10),(-10,-5))
    s.addcomponent(poly1, "red", "blue")
    poly2 = ((0,0),(10,-5),(-10,-5))
    s.addcomponent(poly2, "blue", "red")

  3. Now add the Shape to the Screen’s shapelist and use it:

    register_shape("myshape", s)
    shape("myshape")

Note

The Shape class is used internally by the register_shape()method in different ways. The application programmer has to deal with the Shape class only when using compound shapes like shown above!

Methods of TurtleScreen/Screen and corresponding functions

Most of the examples in this section refer to a TurtleScreen instance calledscreen.

Window control

turtle.bgcolor(*args)

Parameters:

args – a color string or three numbers in the range 0..colormode or a 3-tuple of such numbers

Set or return background color of the TurtleScreen.

screen.bgcolor("orange") screen.bgcolor() 'orange' screen.bgcolor("#800080") screen.bgcolor() (128.0, 0.0, 128.0)

turtle.bgpic(picname=None)

Parameters:

picname – a string, name of a gif-file or "nopic", or None

Set background image or return name of current backgroundimage. If _picname_is a filename, set the corresponding image as background. If picname is"nopic", delete background image, if present. If picname is None, return the filename of the current backgroundimage.

screen.bgpic() 'nopic' screen.bgpic("landscape.gif") screen.bgpic() "landscape.gif"

turtle.clear()

Note

This TurtleScreen method is available as a global function only under the name clearscreen. The global function clear is a different one derived from the Turtle method clear.

turtle.clearscreen()

Delete all drawings and all turtles from the TurtleScreen. Reset the now empty TurtleScreen to its initial state: white background, no background image, no event bindings and tracing on.

turtle.reset()

Note

This TurtleScreen method is available as a global function only under the name resetscreen. The global function reset is another one derived from the Turtle method reset.

turtle.resetscreen()

Reset all Turtles on the Screen to their initial state.

turtle.screensize(canvwidth=None, canvheight=None, bg=None)

Parameters:

If no arguments are given, return current (canvaswidth, canvasheight). Else resize the canvas the turtles are drawing on. Do not alter the drawing window. To observe hidden parts of the canvas, use the scrollbars. With this method, one can make visible those parts of a drawing which were outside the canvas before.

screen.screensize() (400, 300) screen.screensize(2000,1500) screen.screensize() (2000, 1500)

e.g. to search for an erroneously escaped turtle ;-)

turtle.setworldcoordinates(llx, lly, urx, ury)

Parameters:

Set up user-defined coordinate system and switch to mode “world” if necessary. This performs a screen.reset(). If mode “world” is already active, all drawings are redrawn according to the new coordinates.

ATTENTION: in user-defined coordinate systems angles may appear distorted.

screen.reset() screen.setworldcoordinates(-50,-7.5,50,7.5) for _ in range(72): ... left(10) ... for _ in range(8): ... left(45); fd(2) # a regular octagon

Animation control

turtle.delay(delay=None)

Parameters:

delay – positive integer

Set or return the drawing delay in milliseconds. (This is approximately the time interval between two consecutive canvas updates.) The longer the drawing delay, the slower the animation.

Optional argument:

screen.delay() 10 screen.delay(5) screen.delay() 5

turtle.tracer(n=None, delay=None)

Parameters:

Turn turtle animation on/off and set delay for update drawings. If_n_ is given, only each n-th regular screen update is really performed. (Can be used to accelerate the drawing of complex graphics.) When called without arguments, returns the currently stored value of n. Second argument sets delay value (seedelay()).

screen.tracer(8, 25) dist = 2 for i in range(200): ... fd(dist) ... rt(90) ... dist += 2

turtle.update()

Perform a TurtleScreen update. To be used when tracer is turned off.

See also the RawTurtle/Turtle method speed().

Using screen events

turtle.listen(xdummy=None, ydummy=None)

Set focus on TurtleScreen (in order to collect key-events). Dummy arguments are provided in order to be able to pass listen() to the onclick method.

turtle.onkey(fun, key)

turtle.onkeyrelease(fun, key)

Parameters:

Bind fun to key-release event of key. If fun is None, event bindings are removed. Remark: in order to be able to register key-events, TurtleScreen must have the focus. (See method listen().)

def f(): ... fd(50) ... lt(60) ... screen.onkey(f, "Up") screen.listen()

turtle.onkeypress(fun, key=None)

Parameters:

Bind fun to key-press event of key if key is given, or to any key-press-event if no key is given. Remark: in order to be able to register key-events, TurtleScreen must have focus. (See method listen().)

def f(): ... fd(50) ... screen.onkey(f, "Up") screen.listen()

turtle.onclick(fun, btn=1, add=None)

turtle.onscreenclick(fun, btn=1, add=None)

Parameters:

Bind fun to mouse-click events on this screen. If fun is None, existing bindings are removed.

Example for a TurtleScreen instance named screen and a Turtle instance named turtle:

screen.onclick(turtle.goto) # Subsequently clicking into the TurtleScreen will # make the turtle move to the clicked point. screen.onclick(None) # remove event binding again

Note

This TurtleScreen method is available as a global function only under the name onscreenclick. The global function onclick is another one derived from the Turtle method onclick.

turtle.ontimer(fun, t=0)

Parameters:

Install a timer that calls fun after t milliseconds.

running = True def f(): ... if running: ... fd(50) ... lt(60) ... screen.ontimer(f, 250) f() ### makes the turtle march around running = False

turtle.mainloop()

turtle.done()

Starts event loop - calling Tkinter’s mainloop function. Must be the last statement in a turtle graphics program. Must not be used if a script is run from within IDLE in -n mode (No subprocess) - for interactive use of turtle graphics.

Input methods

turtle.textinput(title, prompt)

Parameters:

Pop up a dialog window for input of a string. Parameter title is the title of the dialog window, prompt is a text mostly describing what information to input. Return the string input. If the dialog is canceled, return None.

screen.textinput("NIM", "Name of first player:")

turtle.numinput(title, prompt, default=None, minval=None, maxval=None)

Parameters:

Pop up a dialog window for input of a number. title is the title of the dialog window, prompt is a text mostly describing what numerical information to input. default: default value, minval: minimum value for input, maxval: maximum value for input. The number input must be in the range minval .. maxval if these are given. If not, a hint is issued and the dialog remains open for correction. Return the number input. If the dialog is canceled, return None.

screen.numinput("Poker", "Your stakes:", 1000, minval=10, maxval=10000)

Settings and special methods

turtle.mode(mode=None)

Parameters:

mode – one of the strings “standard”, “logo” or “world”

Set turtle mode (“standard”, “logo” or “world”) and perform reset. If mode is not given, current mode is returned.

Mode “standard” is compatible with old turtle. Mode “logo” is compatible with most Logo turtle graphics. Mode “world” uses user-defined “world coordinates”. Attention: in this mode angles appear distorted ifx/y unit-ratio doesn’t equal 1.

Mode Initial turtle heading positive angles
“standard” to the right (east) counterclockwise
“logo” upward (north) clockwise

mode("logo") # resets turtle heading to north mode() 'logo'

turtle.colormode(cmode=None)

Parameters:

cmode – one of the values 1.0 or 255

Return the colormode or set it to 1.0 or 255. Subsequently r, g, _b_values of color triples have to be in the range 0..*cmode*.

screen.colormode(1) turtle.pencolor(240, 160, 80) Traceback (most recent call last): ... TurtleGraphicsError: bad color sequence: (240, 160, 80) screen.colormode() 1.0 screen.colormode(255) screen.colormode() 255 turtle.pencolor(240,160,80)

turtle.getcanvas()

Return the Canvas of this TurtleScreen. Useful for insiders who know what to do with a Tkinter Canvas.

cv = screen.getcanvas() cv <turtle.ScrolledCanvas object ...>

turtle.getshapes()

Return a list of names of all currently available turtle shapes.

screen.getshapes() ['arrow', 'blank', 'circle', ..., 'turtle']

turtle.register_shape(name, shape=None)

turtle.addshape(name, shape=None)

There are three different ways to call this function:

  1. name is the name of a gif-file and shape is None: Install the corresponding image shape.

    screen.register_shape("turtle.gif")
    Note
    Image shapes do not rotate when turning the turtle, so they do not display the heading of the turtle!

  2. name is an arbitrary string and shape is a tuple of pairs of coordinates: Install the corresponding polygon shape.

    screen.register_shape("triangle", ((5,-3), (0,5), (-5,-3)))

  3. name is an arbitrary string and shape is a (compound) Shapeobject: Install the corresponding compound shape.

Add a turtle shape to TurtleScreen’s shapelist. Only thusly registered shapes can be used by issuing the command shape(shapename).

turtle.turtles()

Return the list of turtles on the screen.

for turtle in screen.turtles(): ... turtle.color("red")

turtle.window_height()

Return the height of the turtle window.

screen.window_height() 480

turtle.window_width()

Return the width of the turtle window.

screen.window_width() 640

Methods specific to Screen, not inherited from TurtleScreen

turtle.bye()

Shut the turtlegraphics window.

turtle.exitonclick()

Bind bye() method to mouse clicks on the Screen.

If the value “using_IDLE” in the configuration dictionary is False(default value), also enter mainloop. Remark: If IDLE with the -n switch (no subprocess) is used, this value should be set to True inturtle.cfg. In this case IDLE’s own mainloop is active also for the client script.

turtle.setup(width=_CFG['width'], height=_CFG['height'], startx=_CFG['leftright'], starty=_CFG['topbottom'])

Set the size and position of the main window. Default values of arguments are stored in the configuration dictionary and can be changed via aturtle.cfg file.

Parameters:

screen.setup (width=200, height=200, startx=0, starty=0) # sets window to 200x200 pixels, in upper left of screen screen.setup(width=.75, height=0.5, startx=None, starty=None) # sets window to 75% of screen by 50% of screen and centers

turtle.title(titlestring)

Parameters:

titlestring – a string that is shown in the titlebar of the turtle graphics window

Set title of turtle window to titlestring.

screen.title("Welcome to the turtle zoo!")

Public classes

class turtle.RawTurtle(canvas)

class turtle.RawPen(canvas)

Parameters:

canvas – a tkinter.Canvas, a ScrolledCanvas or aTurtleScreen

Create a turtle. The turtle has all methods described above as “methods of Turtle/RawTurtle”.

class turtle.Turtle

Subclass of RawTurtle, has the same interface but draws on a defaultScreen object created automatically when needed for the first time.

class turtle.TurtleScreen(cv)

Parameters:

cv – a tkinter.Canvas

Provides screen oriented methods like bgcolor() etc. that are described above.

class turtle.Screen

Subclass of TurtleScreen, with four methods added.

class turtle.ScrolledCanvas(master)

Parameters:

master – some Tkinter widget to contain the ScrolledCanvas, i.e. a Tkinter-canvas with scrollbars added

Used by class Screen, which thus automatically provides a ScrolledCanvas as playground for the turtles.

class turtle.Shape(type_, data)

Parameters:

type_ – one of the strings “polygon”, “image”, “compound”

Data structure modeling shapes. The pair (type_, data) must follow this specification:

type_ data
“polygon” a polygon-tuple, i.e. a tuple of pairs of coordinates
“image” an image (in this form only used internally!)
“compound” None (a compound shape has to be constructed using theaddcomponent() method)

addcomponent(poly, fill, outline=None)

Parameters:

Example:

poly = ((0,0),(10,-5),(0,10),(-10,-5)) s = Shape("compound") s.addcomponent(poly, "red", "blue")

... add more components and then use register_shape()

See Compound shapes.

class turtle.Vec2D(x, y)

A two-dimensional vector class, used as a helper class for implementing turtle graphics. May be useful for turtle graphics programs too. Derived from tuple, so a vector is a tuple!

Provides (for a, b vectors, k number):

Explanation

A turtle object draws on a screen object, and there a number of key classes in the turtle object-oriented interface that can be used to create them and relate them to each other.

A Turtle instance will automatically create a Screeninstance if one is not already present.

Turtle is a subclass of RawTurtle, which doesn’t automatically create a drawing surface - a canvas will need to be provided or created for it. The canvas can be a tkinter.Canvas, ScrolledCanvasor TurtleScreen.

TurtleScreen is the basic drawing surface for a turtle. Screen is a subclass of TurtleScreen, and includes some additional methods for managing its appearance (including size and title) and behaviour. TurtleScreen’s constructor needs a tkinter.Canvas or aScrolledCanvas as an argument.

The functional interface for turtle graphics uses the various methods ofTurtle and TurtleScreen/Screen. Behind the scenes, a screen object is automatically created whenever a function derived from a Screenmethod is called. Similarly, a turtle object is automatically created whenever any of the functions derived from a Turtle method is called.

To use multiple turtles on a screen, the object-oriented interface must be used.

Help and configuration

How to use help

The public methods of the Screen and Turtle classes are documented extensively via docstrings. So these can be used as online-help via the Python help facilities:

help(penup)
Help on function penup in module turtle:
penup()
Pull the pen up -- no drawing when moving.
Aliases: penup | pu | up
No argument
Example:
penup()

These modified docstrings are created automatically together with the function definitions that are derived from the methods at import time.

Translation of docstrings into different languages

There is a utility to create a dictionary the keys of which are the method names and the values of which are the docstrings of the public methods of the classes Screen and Turtle.

turtle.write_docstringdict(filename='turtle_docstringdict')

Parameters:

filename – a string, used as filename

Create and write docstring-dictionary to a Python script with the given filename. This function has to be called explicitly (it is not used by the turtle graphics classes). The docstring dictionary will be written to the Python script _filename_.py. It is intended to serve as a template for translation of the docstrings into different languages.

If you (or your students) want to use turtle with online help in your native language, you have to translate the docstrings and save the resulting file as e.g. turtle_docstringdict_german.py.

If you have an appropriate entry in your turtle.cfg file this dictionary will be read in at import time and will replace the original English docstrings.

At the time of this writing there are docstring dictionaries in German and in Italian. (Requests please to glingl@aon.at.)

How to configure Screen and Turtles

The built-in default configuration mimics the appearance and behaviour of the old turtle module in order to retain best possible compatibility with it.

If you want to use a different configuration which better reflects the features of this module or which better fits to your needs, e.g. for use in a classroom, you can prepare a configuration file turtle.cfg which will be read at import time and modify the configuration according to its settings.

The built in configuration would correspond to the following turtle.cfg:

width = 0.5 height = 0.75 leftright = None topbottom = None canvwidth = 400 canvheight = 300 mode = standard colormode = 1.0 delay = 10 undobuffersize = 1000 shape = classic pencolor = black fillcolor = black resizemode = noresize visible = True language = english exampleturtle = turtle examplescreen = screen title = Python Turtle Graphics using_IDLE = False

Short explanation of selected entries:

There can be a turtle.cfg file in the directory where turtle is stored and an additional one in the current working directory. The latter will override the settings of the first one.

The Lib/turtledemo directory contains a turtle.cfg file. You can study it as an example and see its effects when running the demos (preferably not from within the demo-viewer).

turtledemo — Demo scripts

The turtledemo package includes a set of demo scripts. These scripts can be run and viewed using the supplied demo viewer as follows:

Alternatively, you can run the demo scripts individually. For example,

python -m turtledemo.bytedesign

The turtledemo package directory contains:

The demo scripts are:

Name Description Features
bytedesign complex classical turtle graphics pattern tracer(), delay,update()
chaos graphs Verhulst dynamics, shows that computer’s computations can generate results sometimes against the common sense expectations world coordinates
clock analog clock showing time of your computer turtles as clock’s hands, ontimer
colormixer experiment with r, g, b ondrag()
forest 3 breadth-first trees randomization
fractalcurves Hilbert & Koch curves recursion
lindenmayer ethnomathematics (indian kolams) L-System
minimal_hanoi Towers of Hanoi Rectangular Turtles as Hanoi discs (shape, shapesize)
nim play the classical nim game with three heaps of sticks against the computer. turtles as nimsticks, event driven (mouse, keyboard)
paint super minimalistic drawing program onclick()
peace elementary turtle: appearance and animation
penrose aperiodic tiling with kites and darts stamp()
planet_and_moon simulation of gravitational system compound shapes,Vec2D
rosette a pattern from the wikipedia article on turtle graphics clone(),undo()
round_dance dancing turtles rotating pairwise in opposite direction compound shapes, clone shapesize, tilt, get_shapepoly, update
sorting_animate visual demonstration of different sorting methods simple alignment, randomization
tree a (graphical) breadth first tree (using generators) clone()
two_canvases simple design turtles on two canvases
yinyang another elementary example circle()

Have fun!

Changes since Python 2.6

Changes since Python 3.0