Turtle graphics is a popular way for introducing programming to kids. It was part of the original Logo programming language developed by Wally Feurzig and Seymour Papert in 1966.
Imagine a robotic turtle starting at (0, 0) in the x-y plane. 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 command turtle.left(25), and it rotates in-place 25 degrees clockwise.
By combining together these and similar commands, intricate shapes and pictures can easily be drawn.
The turtle module is an extended reimplementation of the same-named module from the Python standard distribution up to version Python 2.5.
It tries to keep the merits of the old turtle module and to be (nearly) 100% compatible with it. This means in the first place to enable the learning programmer to use all the commands, classes and methods interactively when using the module from within IDLE run with the -n switch.
The turtle module provides turtle graphics primitives, in both object-oriented and procedure-oriented ways. Because it uses Tkinter for the underlying graphics, it needs a version of python installed with Tk support.
The object-oriented interface uses essentially two+two classes:
The TurtleScreen class defines graphics windows as a playground for the drawing turtles. Its constructor needs a Tkinter.Canvas or a ScrolledCanvas as argument. It should be used when turtle is used as part of some application.
Derived from TurtleScreen is the subclass Screen. Screen is implemented as sort of singleton, so there can exist only one instance of Screen at a time. It should be used when turtle is used as a standalone tool for doing graphics.
All methods of TurtleScreen/Screen also exist as functions, i.e. as part of the procedure-oriented interface.
RawTurtle (alias: RawPen) defines Turtle objects which draw on a TurtleScreen. Its constructor needs a Canvas, ScrolledCanvas or TurtleScreen as argument, so the RawTurtle objects know where to draw.
Derived from RawTurtle is the subclass Turtle (alias: Pen), which draws on “the” Screen - instance which is automatically created, if not already present.
All methods of RawTurtle/Turtle also exist as functions, i.e. part of the procedure-oriented interface.
The procedural interface provides functions which are derived from the methods of the classes Screen and Turtle. They have the same names as the corresponding methods. A screen object is automativally created whenever a function derived from a Screen method is called. An (unnamed) turtle object is automatically created whenever any of the functions derived from a Turtle method is called.
To use multiple turtles an a screen one has to use the object-oriented interface.
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.
Most of the examples in this section refer to a Turtle instance called turtle.
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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)
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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)
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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
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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
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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)
| Parameters: |
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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)
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Set the turtle’s first coordinate to y, leave second coordinate unchanged.
>>> turtle.position()
(0.00, 40.00)
>>> turtle.sety(-10)
>>> turtle.position()
(0.00, -10.00)
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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
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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.circle(50)
>>> turtle.circle(120, 180) # draw a semicircle
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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.dot()
>>> turtle.fd(50); turtle.dot(20, "blue"); turtle.fd(50)
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")
>>> turtle.stamp()
13
>>> turtle.fd(50)
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Delete stamp with given stampid.
>>> turtle.color("blue")
>>> astamp = turtle.stamp()
>>> turtle.fd(50)
>>> turtle.clearstamp(astamp)
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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):
... turtle.stamp(); turtle.fd(30)
>>> turtle.clearstamps(2)
>>> turtle.clearstamps(-2)
>>> turtle.clearstamps()
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()
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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)
Return the turtle’s current location (x,y) (as a Vec2D vector).
>>> turtle.pos()
(0.00, 240.00)
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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.pos()
(10.00, 10.00)
>>> turtle.towards(0,0)
225.0
Return the turtle’s x coordinate.
>>> reset()
>>> turtle.left(60)
>>> turtle.forward(100)
>>> print turtle.xcor()
50.0
Return the turtle’s y coordinate.
>>> reset()
>>> turtle.left(60)
>>> turtle.forward(100)
>>> print turtle.ycor()
86.6025403784
Return the turtle’s current heading (value depends on the turtle mode, see mode()).
>>> turtle.left(67)
>>> turtle.heading()
67.0
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Return the distance from the turtle to (x,y), the given vector, or the given other turtle, in turtle step units.
>>> turtle.pos()
(0.00, 0.00)
>>> turtle.distance(30,40)
50.0
>>> joe = Turtle()
>>> joe.forward(77)
>>> turtle.distance(joe)
77.0
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Set angle measurement units, i.e. set number of “degrees” for a full circle. Default value is 360 degrees.
>>> turtle.left(90)
>>> turtle.heading()
90
>>> turtle.degrees(400.0) # angle measurement in gon
>>> turtle.heading()
100
Set the angle measurement units to radians. Equivalent to degrees(2*math.pi).
>>> turtle.heading()
90
>>> turtle.radians()
>>> turtle.heading()
1.5707963267948966
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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
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Return or set the pen’s attributes in a “pen-dictionary” with the following key/value pairs:
This dicionary 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)
>>> turtle.pen()
{'pensize': 10, 'shown': True, 'resizemode': 'auto', 'outline': 1,
'pencolor': 'red', 'pendown': True, 'fillcolor': 'black',
'stretchfactor': (1,1), 'speed': 3}
>>> penstate=turtle.pen()
>>> turtle.color("yellow","")
>>> turtle.penup()
>>> turtle.pen()
{'pensize': 10, 'shown': True, 'resizemode': 'auto', 'outline': 1,
'pencolor': 'yellow', 'pendown': False, 'fillcolor': '',
'stretchfactor': (1,1), 'speed': 3}
>>> p.pen(penstate, fillcolor="green")
>>> p.pen()
{'pensize': 10, 'shown': True, 'resizemode': 'auto', 'outline': 1,
'pencolor': 'red', 'pendown': True, 'fillcolor': 'green',
'stretchfactor': (1,1), 'speed': 3}
Return True if pen is down, False if it’s up.
>>> turtle.penup()
>>> turtle.isdown()
False
>>> turtle.pendown()
>>> turtle.isdown()
True
Return or set the pencolor.
Four input formats are allowed:
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.
>>> turtle.pencolor("brown")
>>> tup = (0.2, 0.8, 0.55)
>>> turtle.pencolor(tup)
>>> turtle.pencolor()
"#33cc8c"
Return or set the fillcolor.
Four input formats are allowed:
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")
>>> col = turtle.pencolor()
>>> turtle.fillcolor(col)
>>> turtle.fillcolor(0, .5, 0)
Return or set pencolor and fillcolor.
Several input formats are allowed. They use 0 to 3 arguments as follows:
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")
>>> colormode(255)
>>> color((40, 80, 120), (160, 200, 240))
>>> color()
("#285078", "#a0c8f0")
See also: Screen method colormode().
Return fillstate (True if filling, False else).
>>> turtle.begin_fill()
>>> if turtle.filling():
... turtle.pensize(5)
else:
... turtle.pensize(3)
To be called just before drawing a shape to be filled.
>>> turtle.color("black", "red")
>>> turtle.begin_fill()
>>> turtle.circle(60)
>>> turtle.end_fill()
Delete the turtle’s drawings from the screen, re-center the turtle and set variables to the default values.
>>> turtle.position()
(0.00,-22.00)
>>> turtle.heading()
100.0
>>> turtle.reset()
>>> turtle.position()
(0.00,0.00)
>>> turtle.heading()
0.0
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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)
Make the turtle visible.
>>> turtle.hideturtle()
>>> turtle.showturtle()
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.hideturtle()
Return True if the Turtle is shown, False if it’s hidden.
>>> turtle.hideturtle()
>>> print turtle.isvisible():
False
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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()
"arrow"
>>> turtle.shape("turtle")
>>> turtle.shape()
"turtle"
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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()
"noresize"
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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 shapes’s outline.
>>> turtle.resizemode("user")
>>> turtle.shapesize(5, 5, 12)
>>> turtle.shapesize(outline=8)
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Rotate the turtleshape by angle from its current tilt-angle, but do not change the turtle’s heading (direction of movement).
>>> turtle.shape("circle")
>>> turtle.shapesize(5,2)
>>> turtle.tilt(30)
>>> turtle.fd(50)
>>> turtle.tilt(30)
>>> turtle.fd(50)
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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).
>>> turtle.shape("circle")
>>> turtle.shapesize(5,2)
>>> turtle.settiltangle(45)
>>> stamp()
>>> turtle.fd(50)
>>> turtle.settiltangle(-45)
>>> stamp()
>>> turtle.fd(50)
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.shape("circle")
>>> turtle.shapesize(5,2)
>>> turtle.tilt(45)
>>> turtle.tiltangle()
45
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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
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Bind fun to mouse-button-release events on this turtle. If fun is None, 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.
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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).
Return the last recorded polygon.
>>> p = turtle.get_poly()
>>> turtle.register_shape("myFavouriteShape", p)
Create and return a clone of the turtle with same position, heading and turtle properties.
>>> mick = Turtle()
>>> joe = mick.clone()
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 0x01417350>
>>> turtles()
[<turtle.Turtle object at 0x01417350>]
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 0x01417710>
>>> ts.bgcolor("pink")
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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 is None, the undobuffer is disabled.
>>> turtle.setundobuffer(42)
Return number of entries in the undobuffer.
>>> while undobufferentries():
... undo()
To use compound turtle shapes, which consist of several polygons of different color, you must use the helper class Shape explicitly as described below:
Create an empty Shape object of type “compound”.
Add as many components to this object as desired, using the addcomponent() 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")
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!
Most of the examples in this section refer to a TurtleScreen instance called screen.