How to time execution time of a batch of code in Python?

Question

I found this question and answer here on StackOverflow.

Python - time.clock() vs. time.time() - accuracy?

Here is some code I'm trying to run:

import sys
import time
import timeit

if (len(sys.argv) > 1):
  folder_path = sys.argv[1]
  if not os.path.isdir(folder_path):
    print "The folder you provided doesn't exist"    
  else:
    print_console_headers()    
    rename_files_to_title_case(folder_path)
    #start the timer.
    #do some freaky magic here.
    #end the timer.

else:
  print "You must provide a path to a folder."

def print_console_headers():
  print "Renaming files..."
  print "--------------------"
  return

def rename_files_to_title_case():  
  """this is just for testing purposes"""  
  L = []
  for i in range(100):
      L.append(i)

if __name__ == '__main__':
    from timeit import Timer
    t = Timer("test()", "from __main__ import test")
    print t.timeit()

How would I give timeit a function with a parameter that's been saved elsewhere?

This is something I've written in Ruby that gave me results in clean code, maybe this helps for suggestions.

start_time = Time.now

folder_path = ARGV[0]
i = 0
Dir.glob(folder_path + "/*").sort.each do |f|
    filename = File.basename(f, File.extname(f))
    File.rename(f, folder_path + "/" + filename.gsub(/\b\w/){$&.upcase} + File.extname(f))
    i += 1
end

puts "Renaming complete."
puts "The script renamed #{i} file(s) correctly."
puts "----------"
puts "Running time is #{Time.now - start_time} seconds"

Greg Hewgill · Accepted Answer · 2012-01-17 07:08:29Z

35

This is how I typically write time measurement code in Python:

start_time = time.time()

# ... do stuff

end_time = time.time()
print("Elapsed time was %g seconds" % (end_time - start_time))

As mentioned in the post you linked to, time.clock() is not appropriate for measuring elapsed time since it reports the amount of CPU time used by your process only (at least on Unix systems). Using time.time() is cross-platform and reliable.

edited Jan 17, 2012 at 7:08

answered Jan 17, 2012 at 4:25

Greg Hewgill

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5 Comments

jfs Over a year ago

timeit uses time.clock() on Windows. from timeit import default_timer as timer; start_time = timer(); ... allows to switch between time.time() on *nix and time.clock() on Windows automatically or later It might use time.walltime().

Greg Hewgill Over a year ago

@J.F.Sebastian: I don't think the OP is looking for the functionality of time.clock(), which is why I don't think timeit is an appropriate choice.

jfs Over a year ago

On Windows time.clock() measures walltime i.e., your remark: "it reports the amount of CPU time used by your process only." might be incorrect.

Greg Hewgill Over a year ago

@J.F.Sebastian: That's true. I've clarified my answer.

Only Bolivian Here Over a year ago

Now this is a good answer, not that "Google it" elitist "answer" given before.

Matt Alcock · Accepted Answer · 2013-02-28 13:07:34Z

16

I would use a timing decorator and place the code you want to time into a function.

import time

def timeit(f):

    def timed(*args, **kw):

        ts = time.time()
        result = f(*args, **kw)
        te = time.time()

        print 'func:%r args:[%r, %r] took: %2.4f sec' % \
          (f.__name__, args, kw, te-ts)
        return result

    return timed

Using the decorator is easy either use annotations.

@timeit
def compute_magic(n):
     #function definition
     #....

Or re-alias the function you want to time.

compute_magic = timeit(compute_magic)

My blog post here has more information. http://blog.mattalcock.com/2013/2/24/timing-python-code/

answered Feb 28, 2013 at 13:07

Matt Alcock

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Comments

user621769 · Accepted Answer · 2012-01-17 09:52:27Z

4

A fun way to time functions is by using decorators and wrapper functions. One of the functions I use for this is:

import time

def print_timing(func):
    def wrapper(*arg):
        t1 = time.time()
        res = func(*arg)
        t2 = time.time()
        string = '| %s took %0.3f ms |' % (func.func_name, (t2-t1)*1000.0)
        print
        print '-'*len(string)
        print string
        print '-'*len(string)
        print
        return res
    return wrapper

Any function decorated by @print_timing, will print print the time it took to stdout

@print_timing
def some_function(text):
    print text

This makes it very convenient to time specific functions.

answered Jan 17, 2012 at 9:52

user621769

Comments

DmitrySemenov · Accepted Answer · 2015-01-09 18:39:03Z

2

If you need to measure a timing of specific lines of code within the function, when decorator can't help there is a solution

import time
from time import sleep

class TT(object):
    def __init__(self):
        self.start = time.time()
    def __str__(self):
        return str(time.time() - self.start)


timeit = TT()

sleep(1)
print timeit

sleep(2)
print timeit

will print:

1.0
3.00

answered Jan 9, 2015 at 18:39

DmitrySemenov

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