Python Turtle: Recursive function

Question

I am having trouble figuring out how to create a function that draws a capital I based on a user input. If the user input is 1, it draws one I, if it's 2 it draws 2 I's, in this pattern seen below.

I can manually do the first 2 levels just by using simple turtle methods but how do you recursively do this so it will do it for higher levels?

def my_turtle_function(n):
    my_win = turtle.Screen()
    my_turtle = turtle.Turtle()
    my_turtle.speed(2)
    my_turtle.left(90)
    if n == 1:
        my_turtle.forward(100)
        my_turtle.right(90)
        my_turtle.forward(100)
        my_turtle.forward(-200)
        my_turtle.forward(100)
        my_turtle.right(90)
        my_turtle.forward(200)
        my_turtle.right(90)
        my_turtle.forward(100)
        my_turtle.forward(-200)
        my_turtle.forward(100)
        my_turtle.right(90)
        my_turtle.forward(100)

Sorry, but we are not going to do all the work for you. We might give you some pointers and you have to write the code, then show what you did and we will comment. First pointer: Write a separate function that take a set of coordinates as the origin (where the arrow is) and a zoom level (maybe a float, defaults to 1.0) as arguments and draws the level 1 structure based from the argument. — Klaus D.
– Klaus D., Commented Oct 15, 2015 at 9:45

xiº · Accepted Answer · 2015-10-15 10:45:30Z

1

import turtle


def move_me(trt, step, n):
    while n > 0:
        tmp = trt.heading()
        trt.lt(90)
        trt.fd(step)
        trt.rt(90)
        trt.fd(step)
        move_me(trt, step / 2, n - 1)
        trt.fd(-2 * step)
        move_me(trt, step / 2, n - 1)
        trt.fd(step)
        trt.rt(90)
        trt.fd(2 * step)
        trt.rt(90)
        trt.fd(step)
        move_me(trt, step / 2, n - 1)
        trt.fd(-2 * step)
        move_me(trt, step / 2, n - 1)
        trt.fd(step)
        trt.rt(90)
        trt.fd(step)
        n -= 1
        trt.seth(tmp)

my_win = turtle.Screen()
my_turtle = turtle.Turtle()
my_turtle.speed(10)
move_me(my_turtle, 200, 3)

answered Oct 15, 2015 at 10:45

xiº

4,7173 gold badges31 silver badges43 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

tobias_k · Accepted Answer · 2015-10-15 09:56:32Z

If you want to do it recursively, you have to call the function again, with different parameters, e.g. with the "level" being one smaller, and the strokes being only half as long. Make sure that the turtle is in the same place and facing the same direction at the start and at the end of the method, then just call the function again when you are at the corners.

Here's some pseudo-code

def my_turtle_function(t, length, n):
    if n > 0:
        move up and left by length, face north
        call my_turtle_function(t, length/2, n-1)
        move right, right by length, face north
        call my_turtle_function(t, length/2, n-1)
        move left, down, down, left by length, face north
        call my_turtle_function(t, length/2, n-1)
        move right, right by length, face north
        call my_turtle_function(t, length/2, n-1)
        move back to starting point

You can also make the code a bit shorter by using loops for the two halves of the 'I' and the two sides of the bar.

Collectives™ on Stack Overflow

Python Turtle: Recursive function

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related