turtle graphics - Need help making a Hilbert Curve using numbers in Python

Question

I want to make a function that will create a Hilbert Curve in python using numbers. The parameters for the function would be a number and that will tell the function how many times it should repeat. To make a Hilbert Curve you start with 'L', then that turns into '+RF-LFL-FR+', and then 'R' turns into '-LF+RFR+FL-' How should I do this?

#Here is what I've made so far
def hilbert(num):
  s = 'L'
  for i in range(num-1):
    s = s.replace('L','+RF-LFL-FR+')
    b = 'R'
    for i in range(num-1):
      b = b.replace('R','-LR+RFR+FL-')
      end = s + b
  return end

It crashes completely when you enter 1, I tried to use to code I made for the Koch snowflake but I wasn't sure how to use the two variables.

#Here is the results for when I use the function
hilbert(1)
#It returns
a crash bruh
hilbert()
#It returns 
'+RF-+RF-LFL-FR+F+RF-LFL-FR+-FR+-L-LR+RFR+FL-+-LR+RFR+FL-F-LR+RFR+FL-+FL-'


#Here is what I want it to return
hilbert(1)
'L'
hilbert(3)
'+-LF+RFR+FL-F-+RF-LFL-FR+F+RF-LFL-FR+-F-LF+RFR+FL-+'

I'm not that good at the range loop, how should I do this?

Answer 1

In the code you provided you are testing with # 1 as input. In this case:

for i in range(num-1):

is not fulfilled and your for-loop is never initialized since your i is already past that range.

Below you can see a sample code that you can use as reference when playing with Hilbert Curve:

import turtle

turtle.speed(speed=10)  # Fastest

hilbert_seq = "a"

for _ in range(5):
    new_seq = ""
    for char in hilbert_seq:
        if char == "a":
            new_seq += "-bF+aFa+Fb-"
        elif char == "b":
            new_seq += "+aF-bFb-Fa+"
        else:
            new_seq += char
    hilbert_seq = new_seq

for char in hilbert_seq:
    if char == "F":
        turtle.forward(9)
    elif char == "+":
        turtle.right(90)
    elif char == "-":
        turtle.left(90)

Screenshot from the above sample code: