Python - Compute the factorial of N with recursion (among others)

# Calculating the factorial of a number 
# is a good way to practice recursion. Below 
# are examples of both recursive and iterative 
# approaches to calculating a factorial. Of course 
# python has its own builtin math module that 
# can also take care of factorials. 
 
import math
 
# A recursive function to calculate the 
# factorial of N 
def recursiveFactorial(n):
    if n == 1:
        return n
    return n * recursiveFactorial(n - 1)
 
# Iterative calculation of the factorial 
# of N 
def iterativeFactorial(n):
    result = 1
    while n > 1:
        result *= n
        n = n-1
    return result
 
# Builtin python math.factorial of N 
def pythonLib(n):
    return math.factorial(n)
 
print("Iterative factorial of 5: ", iterativeFactorial(5))
print("Recursive factorial of 5: ", recursiveFactorial(5))
print("math.factorial of 5: ", pythonLib(5))
 
print("Iterative factorial of 10: ", iterativeFactorial(10))
print("Recursive factorial of 10: ", recursiveFactorial(10))
print("math.factorial of 10: ", pythonLib(10))
 
print("Iterative factorial of 15: ", iterativeFactorial(15))
print("Recursive factorial of 15: ", recursiveFactorial(15))
print("math.factorial of 15: ", pythonLib(15))
 
 
# my results: 
# Iterative factorial of 5:  120 
# Recursive factorial of 5:  120 
# math.factorial of 5:  120 
# Iterative factorial of 10:  3628800 
# Recursive factorial of 10:  3628800 
# math.factorial of 10:  3628800 
# Iterative factorial of 15:  1307674368000 
# Recursive factorial of 15:  1307674368000 
# math.factorial of 15:  1307674368000 
 
 

Python - Roman Numeral to Number Generator

# Convert a roman numeral to a number. 
# 
# If you are interested in roman numerals check out my other post  
# python script that takes a number and generates a roman numeral 
# 
# For a life time of knowledge checkout: 
# http://en.wikipedia.org/wiki/Roman_numerals 
# 
 
 
 
def ConvertRomanNumeralToNumber(roman_numeral):
    number_result = 0
    
    roman_numerals = {
        1:"I", 4:"IV", 5:"V", 9:"IX",
        10:"X", 40:"XL", 50:"L",
        90:"XC", 100:"C", 400:"CD",
        500:"D", 900:"CM", 1000:"M"}
 
    # Iterate through the roman numerals.  But you see here that I sort them to 
    # get the largest string size first: "CD" comes before "I" 
    for numeral_value in sorted(roman_numerals,
                                key=lambda roman: len(roman_numerals[roman]),
                                reverse=True):
        keep_converting = True
        while keep_converting:            
            if roman_numeral.find(roman_numerals[numeral_value]) != -1:
                number_result += numeral_value
                roman_numeral = roman_numeral.replace(roman_numerals[numeral_value], "", 1)
            else:
                keep_converting = False
                
    return number_result
 
 
print(ConvertRomanNumeralToNumber("MCDXLIV"))
print(ConvertRomanNumeralToNumber("MMMDCCCLXXXVIII"))
print(ConvertRomanNumeralToNumber("MMMCMXCIX"))
 
# my output: 
#  1444 
#  3888 
#  3999 
 
 

Python - Roman Numeral Generator

# Convert a number to a roman numeral. 
# 
# If you are interested in roman numerals check out my other post to convert roman numerals back to numbers 
# python script that takes roman numerals and generates numbers. 
# 
# To increase your life time of knowledge read up on roman numerals: 
# http://en.wikipedia.org/wiki/Roman_numerals 
 
 
def ConvertNumberToRomanNumeral(number):
    roman_numeral_result = "" 
    
    # Roman numeral dict. Place approved roman numeral key:value pairs 
    # in the dict and they will be used. 
    roman_numerals = {
        1:"I", 4:"IV", 5:"V", 9:"IX",
        10:"X", 40:"XL", 50:"L",
        90:"XC", 100:"C", 400:"CD",
        500:"D", 900:"CM", 1000:"M"}
 
    # Iterate from highest to lowest through the roman numerals. 
    for numeral_value in sorted(roman_numerals.keys(), reverse=True):
 
        # Continue replacing large roman numerals while the number is 
        # high enough. 
        while (number >= numeral_value):
            # Build the Roman Numeral string. 
            roman_numeral_result += roman_numerals[numeral_value]
            # Decrease the working number by the roman numeral value just 
            # added to the roman numeral result. 
            number -= numeral_value
 
    return roman_numeral_result
 
 
print(ConvertNumberToRomanNumeral(1444))
print(ConvertNumberToRomanNumeral(3888))
print(ConvertNumberToRomanNumeral(3999))
 
# my output: 
#  MCDXLIV 
#  MMMDCCCLXXXVIII 
#  MMMCMXCIX 
 
 

Python - the final countdown

# There is more than one way to accomplish a task. 
# I needed a method to countdown from a positive 
# number down to 0.  Here are three ways to solve 
# the issue.  Of course there are many more possible 
# solutions. 
# 
# I'd like to title this post "The Final Count Down" 
# Listen to this tune whilst perusing the script: 
# www.youtube.com/watch?v=tt_ro2aerQg 
 
 
# Using recursion always makes the girls swoon. 
def recursiveCountdown(number):
    print number
    if number > 0:
        recursiveCountdown(number-1)
 
# Old school while loop.  This solution gets points 
# for being the most obvious. 
def whileLoopCountdown(number):
    while number > -1:
        print number
        number -= 1
 
# Using python's xrange function is the most concise. 
def xrangeCountdown(number):
    for i in xrange(number, -1, -1):
        print i
 
print "It's the final countdown" 
number = input("Enter number: ")
 
print "Recursive..." 
recursiveCountdown(number)
print "While Loop..." 
whileLoopCountdown(number)
print "xrange..." 
xrangeCountdown(number)
 
 
# my output: 
# 
#It's the final countdown 
#Enter number: 5 
#Recursive... 
#5 
#4 
#3 
#2 
#1 
#0 
#While Loop... 
#5 
#4 
#3 
#2 
#1 
#0 
#xrange... 
#5 
#4 
#3 
#2 
#1 
#0 
 
 

python - while loop specified time frame

import time

def looper(timeCount):
   start = time.time()
   keepLooping = True
   while keepLooping:
       if time.time()-start > timeCount:
           keepLooping = False
       else:
           print time.time()-start
       time.sleep(0.1)



if __name__ == '__main__':
       looper(10.0)