how to pass parameters of a function when using timeit.Timer()

Question

This is the outline of a simple program

# some pre-defined constants
A = 1
B = 2

# function that does something critical
def foo(num1, num2):
    # do somet         


        

Answer 1

The functions can use arguments in timeit if these are created using closures, we can add this behaviours by wrapping them in another function.

def foo(num1, num2):
    def _foo():
        # do something to num1 and num2
        pass
    return _foo

A = 1
B = 2

import timeit
t = timeit.Timer(foo(A,B))  
print(t.timeit(5))

or shorter, we can use functools.partial instead of explicit closures declaration

def foo(num1, num2):
    # do something to num1 and num2
    pass

A = 1
B = 2

import timeit, functools
t = timeit.Timer(functools.partial(foo, A, B)) 
print(t.timeit(5))

EDIT using lambda, thanks @jupiterbjy

we can use lambda function without parameters instead of functools library

def foo(num1, num2):
    # do something to num1 and num2
    pass

A = 1
B = 2

import timeit
t = timeit.Timer(lambda: foo(A, B)) 
print (t.timeit(5))

Answer 2

I was playing around with timing in Python 3.7 today and trying to pass functions and variables into the timer. This is what I came up with.

import re

text = "This         is      a  test of the      emergency broadcast       system"

def regex(text):
    return re.sub(r"(\s)\1{1,}", r"\1", text)

def loop_while(text):
    if "  " in text:
        while "  " in text:
            text = text.replace("  ", " ")

    return text

if __name__ == "__main__":
    import timeit

    callable_functions = [item for item in locals().items() if callable(item[1])]

    for func_name, func in callable_functions:
        elapsed_time = timeit.timeit(f"{func_name}(text)", globals=globals(), number=100000)
        print(f"{func_name}: {elapsed_time} \n{func(text)}\n")

This outputs:

regex: 1.378352418
This is a test of the emergency broadcast system

loop_while: 0.15858950299999997
This is a test of the emergency broadcast system

Then all it takes to test a new version is adding in a new function. Something like:

def split_join(text):
    return " ".join(text.split())

Now it outputs:

regex: 1.378352418
This is a test of the emergency broadcast system

loop_while: 0.15858950299999997
This is a test of the emergency broadcast system

split_join: 0.05700970800000005
This is a test of the emergency broadcast system

Answer 3

Another option is to bind the function to its arguments via functools (similar to std::bind). Then you don't need to pass arguments to timeit, the callable returned by functool.partial takes care of that:

    def findMax(n):#n is an array
        m = 0
        c = 0
        for i in range(len(n)):
            c += 1
            if m < n[i]:
                m = n[i]
        return m, c


import timeit
import functools
a = [6, 2, 9, 3, 7, 4, 5]
t = timeit.Timer(functools.partial(findMax,a))
t.timeit(100)

Answer 4

Your function needs to be define in the setup string. A good way to do this is by setting up your code in a module, so you simple have to do

t = timeit.Timer("foo(num1, num2)", "from myfile import foo")
t.timeit(5)

Otherwise, you'll have to define all of the setup as a string inside the setup statement.

setup = """
 # some pre-defined constants
A = 1
B = 2

# function that does something critical
def foo(num1, num2):
    # do something

# main program.... do something to A and B
for i in range(20):
    # do something to A and B
    # and update A and B during each iteration
"""

t = timeit.Timer("foo(num1, num2)", setup)
t.timeit(5)

Something awesome I just found out about is a shortcut for iPython that uses cProfile.

def foo(x, y):
    print x*y

%prun foo("foo", 100)

Answer 5

You have to create the variable within the setup string. Here I import the function, and create one of the variables that i pass to it. I also set one of the variables by casting it to the stmt string

SETUP = '''
from __main__ import policy_iteration
from environments.gridworld import GridworldEnv

env = GridworldEnv()
'''

discount = 5
timeit.timeit("policy_iteration(env,discount_factor="+str(discount)+")",
                          setup= SETUP,
                          number=10))

Answer 6

This should work:

import timeit

def f(x,y):
    return x*y

x = 5
y = 7

print(timeit.timeit(stmt='f(x,y)',
                    setup='from __main__ import f, x, y',
                    number=1000))