CODEWITHSUNDEEP
pythonturtle-graphicspython-turtle
TechBee
TechBee

Reputation: 31

Spiral Traversing Python Turtle

I have been trying to solve this for the past few days. It actually works but not in the way I want. The problem is that it starts spiraling from the top left (picture 1) rather than from the bottom right (picture 2), which is what I want. I'm a beginner, and I'm not aware of many of turtle's methods or functions, so please answer my question with your code for better understanding:

import turtle
tur=turtle.Turtle()
tur.penup()
tur.setpos(-250,250)
dot_distance=15
def spiral(r,c):
  #r=row,#c=col
  ri=0;ci=0
  #ri=row_index,ci=col_index
  while(ri<r and ci<c):
    
     for i in range(c-1,ci-1,-1):
        tur.dot()
        tur.forward(dot_distance)
        
     r-=1
     tur.right(90)
    
     for i in range(r-1,ri-1,-1):
        tur.dot()
        tur.forward(dot_distance)
        
     ci+=1
     tur.right(90)
    
     for i in range(ci,c):
        tur.dot()
        tur.forward(dot_distance)
        
     ri+=1
     tur.right(90)
    
     for i in range(ri,r):
        tur.dot()
        tur.forward(dot_distance)
        
     c-=1
     tur.right(90)
   
spiral(20,20)

Actual output is the 1st picture, but I want it like the 2nd picture, where it starts spiraling from bottom right rather than top left:

][1]][1]1

:

Upvotes: 1

Views: 468

Answers (3)

Red
Red

Reputation: 27567

This code will make a turtle spiral around, leaving a dot trail behind, and the resulting image will be perfectly in the center of the screen:

from turtle import Turtle

tur = Turtle()
tur.setheading(180)
tur.penup()
dot_distance = 10

def spiral(r,c):
    tur.setpos(c*dot_distance/2, -r*dot_distance/2)
    r -= 1
    while r+1 and c:
        for _ in range(c):
            tur.forward(dot_distance)
            tur.dot()
        c -= 1
        tur.right(90)
        for _ in range(r):
            tur.forward(dot_distance)
            tur.dot()
        r -= 1
        tur.right(90)
        
spiral(20,20)

Output:

enter image description here

You can see that after each line is drawn, I decrement the variable (r or c) by 1,
so this while loop: while r+1 and c: tells python that while there are still any dots left for each variable,
continue drawing lines.

Upvotes: 0

cdlane
cdlane

Reputation: 41872

Simply fixing the starting direction isn't enough, we also need to fix the starting position. And while we're at it, polish up your code:

from turtle import Screen, Turtle

DOT_DISTANCE = 15

def spiral(row, col):

    while col > 0 < row:

        for _ in range(col):
            turtle.forward(DOT_DISTANCE)
            turtle.dot()

        row -= 1
        turtle.right(90)

        for _ in range(row):
            turtle.forward(DOT_DISTANCE)
            turtle.dot()

        col -= 1
        turtle.right(90)

screen = Screen()

turtle = Turtle()
turtle.speed('fastest')  # because I have no patience
turtle.penup()
turtle.setpos(150, -150)
turtle.setheading(180)

spiral(20, 20)

turtle.hideturtle()
screen.exitonclick()

Upvotes: 1

Dash
Dash

Reputation: 1299

You're just missing tur.setheading(180) after tur.setpos()

From the docs:

Set the orientation of the turtle to to_angle: Some common angles in degrees

0: East
90: North
180: West
270: South

Upvotes: 1

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