Python function producing unexpected output

Question

I have the following python code:

from time import time


def program1(a,b):
    for trial in range(5):
        start = time()
        a + b
        print (time() - start)
program1(27,59)

and according to the tutorial should produce this output:

9.53674316406e-07
2.14576721191e-06
2.14576721191e-06
3.09944152832e-06
9.53674316406e-07

Instead it produces:

0.0
0.0
0.0
0.0
0.0
>>>

I am trying to use it demonstrate the concept of time/space complexity.

Can anyone shed any light on the output and why it is not accepting the parameters?

a+b is happening too fast to have any resolution when time() - start is computed. — Rafael Barros, Sep 10 '21 at 18:58
Can you suggest how I can achieve the output as shown in the tutorial in order to demonstrate this to students, or a better way perhaps that demonstrates — Compoot, Sep 10 '21 at 18:59
@Barmar - but the tutorial (Harvard) suggests that output...what am I missing? — Compoot, Sep 10 '21 at 19:01
If you want to demonstrate time complexity, do something whose time is dependent on `trial` — Barmar, Sep 10 '21 at 19:01
AttributeError: 'builtin_function_or_method' object has no attribute 'sleep' — Compoot, Sep 10 '21 at 19:02
import time doesn't work - start = time() TypeError: 'module' object is not callable — Compoot, Sep 10 '21 at 19:04
Don't have the link unfortunately, but that bit is exactly as explained in the question. Are there any super ones for Big O demo - kid friendly? — Compoot, Sep 10 '21 at 19:08
I guess it's Activity 1 [here](https://docs.google.com/document/d/1TZcKVFYVFDPEBnYPr4nCerz0PrXKrp07WbMWqlT8E4A/mobilebasic)? Anyway, the problem is mainly using the `time()` function, especially if you're on Windows. — no comment, Sep 10 '21 at 19:13

Rafael Barros · Answer 1 · 2021-09-10T19:11:21.167

0

Try this:

from time import time, sleep
import random


def program1(a,b):
    for trial in range(5):
        start = time() # gets current time

        time_to_sleep = random.random() # random() returns a number between 0 and 1
        
        # sleep will block the execution here for the number of seconds passed (0.5 is half a second for instance).
        sleep(time_to_sleep) 
        print (time() - start)
program1(27,59)

I added the random to make it a little bit unpredictable.

edited Sep 10 '21 at 19:11

answered Sep 10 '21 at 19:04

Rafael Barros

2,738
1
21
28

Rafael - will try - could you add some comments (for teaching purposes). Explaining what is happening. For instance, what exactly is time() doing (calling what). and the sleep.random – Compoot Sep 10 '21 at 19:06

Python function producing unexpected output

1 Answers1