Comparing primality checking functions

isPrime.py

"""
Compare different methods of checking for a numbers primality.

"""
import math
import time
import sys


def isPrime(n):
    """Check if a number is a prime number."""
    if n == 2:
        return True
    for i in range(3, int(math.sqrt(n) + 1), 2):
        if n % i == 0 and n != i:
            return False
    return True

def isPrime2(n):
    """Check if a number is a prime number."""
    if n == 2:
        return True
    return (len([x for x in range(3, int(math.sqrt(n) + 1), 2) if n % x == 0]) == 0)

def isPrime3(n):
    """Check if a number is a prime number."""
    if n == 2:
        return True
    return all(map(lambda x: n % x != 0, range(3, int(math.sqrt(n) + 1), 2)))

def findAverage(func, runs, primeNumber):
    """
    Execute a function [runs] number of times, and
    return the average execution time.
    
    """
    avg = 0
    for i in range(runs):
        start = time.time()
        func(primeNumber)
        avg += time.time() - start
    return avg / runs

def output(text):
    """For quickly switching between Python 2 and 3."""
    print(text)

def main():
    runs = 1000
    primeNumber = 32416190071

    testFunctions = {
        'isPrime': isPrime,
        'isPrime2': isPrime2,
        'isPrime3': isPrime3
    }
    output("+------------------------------------------+")
    output("| Using Python v. %-5s                    |" % sys.version.split(' ')[0])
    output("+------------------------------------------+")
    output("| Checking if %-28s |" % (str(primeNumber) + " is a prime"))
    output("+------------------------------------------+")
    output("| Number of runs: %-23s  |" % runs)
    output("+------------------------------------------+")
    output("")
    output("+------------------------------------------+")
    output("| Function Name | Average time to execute  |")
    output("+------------------------------------------+")
    for name, func in testFunctions.items():
        output("| %-13s | %-24s |" % (name, findAverage(func, runs, primeNumber),))
    output("+------------------------------------------+")

if __name__ == '__main__':
    main()

# +------------------------------------------+
# | Using Python v. 3.3.0                    |
# +------------------------------------------+
# | Checking if 32416190071 is a prime       |
# +------------------------------------------+
# | Number of runs: 1000                     |
# +------------------------------------------+
# 
# +------------------------------------------+
# | Function Name | Average time to execute  |
# +------------------------------------------+
# | isPrime       | 0.013823300361633302     |
# | isPrime2      | 0.01397840428352356      |
# | isPrime3      | 0.028225141286849977     |
# +------------------------------------------+

# +------------------------------------------+
# | Using Python v. 2.7.2                    |
# +------------------------------------------+
# | Checking if 32416190071 is a prime       |
# +------------------------------------------+
# | Number of runs: 1000                     |
# +------------------------------------------+
# 
# +------------------------------------------+
# | Function Name | Average time to execute  |
# +------------------------------------------+
# | isPrime       | 0.00974343919754         |
# | isPrime3      | 0.0233035748005          |
# | isPrime2      | 0.0090259552002          |
# +------------------------------------------+