How to stop turtle from drawing even with pen up? - python

I am using the turtle module in python. the problem is that whenever I have the turtle move i will draw even if the pen is up. for example if I run this program:
import turtle
turtle.penup
turtle.goto(0,50)
the turtle will still draw a line when it moves to (0,50)
why is this and how can it be prevented?

It looks like you're not actually calling turtle.penup. Try this:
import turtle
turtle.penup()
turtle.goto(0,50)

You have a typo, you aren't calling the penup method:
import turtle
turtle.penup() #This needs to be a method call
turtle.goto(0,50)

import turtle
turtle.up()
turtle.goto(0,50)
turtle.down()
if you don't put the pen down it will keep on drawing in invisible condition.

This question is super old and definitely has already been answered, but I'll leave this explanation here for future people
"penup" is a method in Python, aka function in other languages. This means that when you want to use it you have it include some parenthesis just so that your code knows what is supposed to be happening
import turtle
turtle.penup()
turtle.goto(0,50)
When you don't include the parenthesis, the code thinks you are talking about a variable, and looks for one called "penup", but there is no variable of that name, so Python throws its hands up and crashes

you called penup without (). with
turtle.penup()
this will work.
Others here said that, but implicitly. trying to ensure it is clear where the typo is.

You should probably try,
turtle.penup()

no it should be something like this:
turtle.up() # This a method call
turtle.goto(0,50) # Part of the method call

Related

Turtle Screen.tracer(0) doesn't stop all animation

I thought using Screen.tracer(0) disabled animation in Python Turtle Graphics. However in the following program, if you comment out screen.update(), there is still some animation happening - the turtle trail gets drawn although the turtle doesn't "move" (or get updated). What is happening here please? Is there way to make updating the screen completely manual?
import turtle
def move():
my_turtle.forward(1)
my_turtle.right(1)
screen.update() # Comment out this line to see issue.
screen.ontimer(move, 10)
screen = turtle.Screen()
my_turtle = turtle.Turtle()
my_turtle.shape("turtle")
screen.tracer(0)
move()
turtle.done()
No, screen.tracer(0) doesn't stop all animation. Some turtle commands like end_fill() invoke screen.update() directly, some like dot() invoke it due to other methods that they in turn invoke. You only advise the system when you call update(), not control it completely.
Put your update() calls where you believe you need them, and don't assume certain methods force an update, otherwise future updates of turtle might break your code. (I.e. someone might actually fix turtle.)
For potentially helpful details, see my tracer() rules of thumb and information about the first argument's numeric value
In turtle.py, forward() calls _go() which sets an endpoint, then calls _goto()
_goto() creates a newline if line segments get above 42
if len(self.currentLine) > 42: # 42! answer to the ultimate question
# of life, the universe and everything
self._newLine()
The value appears to be arbitrary; you could set it to something higher, but then there are pauses where nothing appears to be happening.
def _newLine(self, usePos=True):
"""Closes current line item and starts a new one.
Remark: if current line became too long, animation
performance (via _drawline) slowed down considerably.
"""

Turtle Library in Python

I am having a huge issue using the turtle library. I have to write my initials AR for an assignment. Can anyone help?
import turtle
turtlescreen
turtle.pos(400,400)
turtle.forward()
Here is the code I am trying to use. I am trying to right my initial "AR" with it.
You've managed to cram three errors into four lines of code. First, you don't need this and it's an error:
turtlescreen
so toss it. Second, the pos() function returns the current turtle postion, not set it. So instead of:
turtle.pos(400,400)
You want:
turtle.setpos(400, 400)
and finally, as #Jamie notes, you need to pass a distance (in pixels) to forward(). So instead of:
turtle.forward()
Something like he suggests:
turtle.forward(15)
Complete code:
import turtle
turtle.setpos(400, 400)
turtle.forward(15)
turtle.done()
Your turtle.forward() requires an input variable in pixels. See the documentation for turtle.forward:
Move the turtle forward by the specified distance, in the direction the turtle is headed.
Try changing:
turtle.forward()
to something like:
turtle.forward(15)
There's a few mistakes I can see. Firstly, there is no command called turtlescreen so you can remove that. Next, instead of tom.pos try using tom.setpos(x, y) or tom.goto (x, y). Lastly, you should put a value in tom.forward (length). I also recommend going through the Python Turtle documentation, https://docs.python.org/3.3/library/turtle.html?highlight=turtle

t=turtle.Pen() says turtle doesn't have the attribute Pen

After importing turtle, I keep trying to put t=turtle.Pen() but it says turtle doesn't have the attribute Pen.
I have tried
turtle=turtle.Pen()
t=turtle.Turtle()
myturtle=turtle.Pen()
my turtle =turtle.Turtle()
but every time it says turtle does not have attribute whatever I put as my attribute. Does anyone know why this is happening? I have python version 3.5.0
Here is a brief turtle example:
https://gist.github.com/wolfospealain/af3410a9e71eb2ff7be5625174c4f4c5
#!/usr/bin/python3.5
import turtle
turtle.shape("turtle")
turtle.left(45)
turtle.forward(50)
turtle.right(65)
turtle.circle(150,350)
turtle.home()
big=("Arial", 36, "normal")
turtle.penup()
turtle.goto(-40,150)
turtle.write("Hello World!", font=big)
turtle.home()
turtle.back(20)
turtle.exitonclick()
Notice how you must first import turtle to make the turtle library available to your program.
Notice, too, that all the method names are lower case (for example, turtle.penup()).
I think you probably meant turtle.penup(), which allows you to "move" without drawing.
You can find complete turtle documentation here: https://docs.python.org/3.3/library/turtle.html
Here is a short tutorial you might find helpful: https://www.tutorialspoint.com/turtle-programming-in-python

Invalid syntax for turtle name (python)

I am trying to write a program to draw a flower, but no matter what I do it keeps throwing an "invalid syntax" error for the turtle name. I have taken out all of my other code, tried naming the turtle something different, yet nothing works. Any ideas?
import turtle
def draw_flower():
window = turtle.Screen()
window.bgcolor(#42dff4)
sam = turtle.Turtle()
sam.forward(50)
window.exitonclick()
draw_flower()
Besides quoting the color string, as noted in the comments, your lines of code are in the wrong order. For example, generally nothing should follow window.exitonclick():
window.exitonclick()
draw_flower()
Make it (or window.mainloop()) the last statement of your program as that's when your code ends and the Tk event handler loop begins. I.e. reverse the order of these two statements. The second problem is that the variable window is in the wrong scope:
def draw_flower():
window = turtle.Screen()
...
window.exitonclick()
Since it's defined locally in draw_flower(), it's not available to use globally. Here's a rework of your code addressing both issues:
import turtle
def draw_flower():
sam = turtle.Turtle()
sam.forward(50)
window = turtle.Screen()
window.bgcolor("#42dff4")
draw_flower()
window.exitonclick()

Python turtle.ondrag not working

I've been trying to make a paint program in Python Turtle and for some reason it won't work. I'm using the pen() tool and my code looks like this
from turtle import *
import random
pen()
bgcolor('black')
pencolor('white')
pen.ondrag(pen.goto)
listen()
mainloop()
I've look at this http://docs.python.org/2/library/turtle.html and it says to type turtle.ondrag(turtle.goto) but since I'm using the pen it should work as pen.ondrag but it doesn't, so can someone please clear this up.
Thanks Jellominer
I will simplify and clarify the code given by the questionner:
from turtle import *
ts = Screen(); tu = Turtle()
ts.listen()
ondrag(tu.goto)
mainloop()
This works. You have to click on the turtle and drag it.
First, pen() is not the function you want. Second, although Pen is a synonym for Turtle, pen is not a synonym for turtle. Here's how to go about using ondrag() if you'd like to use Pen instead of Turtle:
from turtle import Pen, Screen, mainloop
def ondrag_handler(x, y):
pen.ondrag(None) # disable handler inside handler
pen.setheading(pen.towards(x, y)) # turn toward cursor
pen.goto(x, y) # move toward cursor
pen.ondrag(ondrag_handler)
screen = Screen()
screen.bgcolor('black')
pen = Pen()
pen.color('white')
pen.shapesize(2) # make it larger so it's easier to drag
pen.ondrag(ondrag_handler)
screen.listen()
mainloop() # screen.mainloop() preferred but not in Python 2
The turtle.ondrag(turtle.goto) makes for a nice short example in the documentation but in reality isn't practical. You want to disable the event handler while handling the event otherwise the events stack up against you. And it's nice to turn the mouse towards your cursor as you drag it.
from turtle import *
ts = Screen()
ondrag(goto)
shapesize(10)
pensize(40)
speed(0)
mainloop()
I think this will surely work.
You can change the size and other things
In here you are using the default turtle .
Sorry but you'll need to take care of the indentation

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