Timing how long a python script runs

This post introduces several ways to find out how long a python script takes to complete its execution.

  • If you are using Linux or Mac OS, in your terminal
$ time ./your_script.py
  • Several ways to do the task by adding a few lines of code in your py script.
import time
startTime = time.time()


print ("It took", time.time() - startTime, "seconds.")

See the following for an example in python 3. 

import time
import functools

startTime = time.time()

print(functools.reduce(lambda x,y: x+y, [47,11,42,13]))

print ("It took", time.time() - startTime, "seconds.")

Another way to do the same thing:

from datetime import datetime
startTime = datetime.now()

#do something

#Python 2: 
print datetime.now() - startTime 

#Python 3: 
print(datetime.now() - startTime)

One more way to do the same thing with a nicely formatted output.

import sys
import timeit

startTime = timeit.default_timer()

#do some nice things...

stopTime = timeit.default_timer()
totalRunningTime = stopTime - startTime

# output running time in a nice format.
mins, secs = divmod(totalRunningTime, 60)
hours, mins = divmod(mins, 60)

sys.stdout.write("Total running time: %d:%d:%d.\n" % (hours, mins, secs))

If you want to compare two blocks of code / functions quickly you can do the following:

import timeit

startTime = timeit.default_timer()
print(timeit.default_timer() - startTime)

startTime2 = timeit.default_timer()
print(timeit.default_timer() - starTime2)

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