Question

I need to figure out the delay between sending a command to change the background color or playing a sound and these events actually occurring using timeit.(I’m on windows, Python 2.73)
I’m doing a reaction time test where I’ll record the time(using time.clock()) before either changing the background color or playing a sound. Then, when the subject presses a key I record the time again and take difference to find the reaction time.
For the sound playing, here’s what I did:

import timeit
t = timeit.Timer(stmt = "winsound.PlaySound('C:\WINDOWS\media\Windows XP Error.wav', winsound.SND_FILENAME)",setup = "import winsound")
n = t.timeit(number = 100) 
print n/100 -0.999  

The 0.999 is the duration of the Windows XP Error.wav in seconds.
This gave me something like 56ms. I’m not sure if its reasonable and if its the right way to do it as well as should I be enabling the garbage collection or not?

---

For the background changing I’m having more problems. Since I’m doing the test in fullscreen mode I tried to put all of these into the setup parameter:

from Tkinter import Tk
root=Tk()
root.overrideredirect(True)
root.geometry("{0}x{1}+0+0".format(root.winfo_screenwidth(),root.winfo_screenheight()))
root.mainloop()

Even though I separate them all with ; I still get syntax errors. When I try it not in full screen
setup = 'from Tkinter import Tk; root=Tk(); root.mainloop()' the window actually opens, yet nothing happens and if I close it I see other errors.Invalid command name "."
The statement that I’m actually measuring is root.configure(background='red').

Answer 1

Here’s an example of a way to create a multi-line setup string for use with timeit:

setup = """
import random
l1 = [random.randrange(100) for _ in xrange(100)]
l2 = [random.randrange(100) for _ in xrange(10)]
"""

Here’s another tip. To get an accurate measurement, it’s important to time things following this basic pattern:

time = min(timeit.repeat(statements, setup=setup, repeat=R, number=N))

With an R of at least 3 (R = 3). This takes the fastest value obtained by doing everything 3 times, which will eliminate differences due to the many other things running on your system in the background.

This doesn’t answer your whole question, but may be helpful in your quest.