Using turtle graphics in Google colab

Question

I am working with a student that uses Google colab. I tried introducing her to turtle graphics. We got this error: TclError: no display name and no $DISPLAY environment variable.

When I try to look up the error all the solutions are very specific to matplotlib. That worked for my student without making any adjustment. I am looking for a solution for this that works more generally or at least works with turtle and tkinter.

The student is using a Chrome book. Google colab is what she uses at school, solving the problem in that environment would be best if possible. Did try to create a Turtle object, but this produced the same error.

I did a search on the error all the post I could find talked bout this problem with matplotlib. The solution in that case was to override what I think is a rendering option by invoking .use('Agg'). I did not see an obvious equivalent for turtle.

I also tried using matplotlib, to see if we got the error that I saw in the postings. We tried a simple matplotlib example and it worked without any changes. The graph output appeared as expected.

import turtle
turtle.forward(100)

I expect the turtle graphics to be drawn in the results. What I actually got were these errors:

---------------------------------------------------------------------------
TclError                                  Traceback (most recent call last)
<ipython-input-7-585bbd158605> in <module>()
----> 1 turtle.forward(100)

5 frames
/usr/lib/python3.6/tkinter/__init__.py in __init__(self, screenName, baseName, className, useTk, sync, use)
   2021                 baseName = baseName + ext
   2022         interactive = 0
-> 2023         self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
   2024         if useTk:
   2025             self._loadtk()

TclError: no display name and no $DISPLAY environment variable

Answer 1

Create an empty code cell, type the following pip command and run it:

!pip3 install ColabTurtle

I recommend you use your turtle like this (in a separate code piece):

import ColabTurtle.Turtle as lia
lia.initializeTurtle(initial_speed=5) 
lia.color('blue')
lia.forward(100)
lia.right(45)
lia.color('red')
lia.forward(50)

You may in fact use direct calls (skip all the lia object ref), but it's not a good idea IMHO since you want your students to get used to using instances. This simplified (less recommended way) would look like this:

import ColabTurtle
forward(100)
right(90)
forward(100)

You are not habituating students to using objects and they cannot see the tool tips (e.g. available methods and properties of the object).