CODEWITHSUNDEEP
pythonturtle-graphics
Newbie
Newbie

Reputation: 376

Python Turtle: Recursive function

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.

enter image description here

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)

Upvotes: 0

Views: 736

Answers (2)

xiº
xiº

Reputation: 4687

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)

enter image description here

Upvotes: 1

tobias_k
tobias_k

Reputation: 82899

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.

Upvotes: 0

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