MacLochlainns Weblog

While working with a programming example for my students, I ran into an interesting run-time error when I changed their approach to importing Python’s random module. Here’s the raised error message:

Traceback (most recent call last):
  File "windowBouncingBalls.py", line 84, in <module>
    speed = [choice([-2,2]), choice([-2,2])]
NameError: name 'choice' is not defined

You raise the missing choice identifier when two things occur. The first thing requires you to use a standard import statement, like the following example, and the second thing requires you to continue to reference the identifier as “choice“.

import random

You can avoid the error by making the import of random like this:

from random import *

Or, you can leave the ordinary import statement and fully qualify the choice identifier with the random module name, like this:

    speed = [random.choice([-2,2]), random.choice([-2,2])]

As always, I hope this helps those who encounter a similar problem.

In teaching, I had a problem because my students have different base operating systems, like Windows 7, Windows 8, Linux, and Mac OS X. I needed a teaching and lecture platform that would let me teach it all (not to mention support their environments). That meant it had to virtualize any of the following with a portable device:

I never considered a manufacturer other than Apple for a laptop since they adopted the Intel chip. Too many of the others sell non-hyperthreaded laptop machines that they market as i5 or i7 64-bit OS machines when they’re not. Some of those vendors disable the hyperthreading facility while others provide motherboards that can’t support hyperthreading. The ones I dislike the most provide a BIOS setting that gives the impression you can enable hyperthreading when you can’t. All Apple devices, MacBook, MacBook Pro, Mac Mini, and Mac Pro do fully support a 64-bit OS and their virtualization.

A MacBook Pro came to mind but the disk space requirements were 1 TB, and that’s too pricey. I went with the Mac Mini because with 16 GB of memory and a 1 TB drive it was only $1,200. Add a wireless keyboard and mighty mouse, and an HDMI and mini-DVI connections, and I had my solution. Naturally, my desktop is a one generation old Mac Pro with 64 GB of memory and 12 TB of disk space, which supports all the virtual machines used for testing. Note to Apple marketing staff: The prior version of the Mac Pro let you pay reasonable (3rd party) prices for the additional memory and disk drives.

The Mac Mini means I can travel anywhere and plug into the console and demo tools and techniques from a myriad set of platforms without the hassle of moving on and off to frequently VM images. It’s a great solution with only one downside, HDMI to DVI sometimes creates purple toned screens. It’s unfortunate because some venues have monitors that don’t support HDMI).