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completed birthdayparadox.py

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cheeks 2025-03-13 21:41:32 +00:00
parent 74ceea588a
commit 9830f6b04b
1 changed files with 43 additions and 1 deletions
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birthdayparadox.py
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@ -21,6 +21,7 @@ def getBirthdays(numberOfBirthdays):
birthdays.append(birthday) birthdays.append(birthday)
return birthdays return birthdays
def getMatch(birthdays): def getMatch(birthdays):
"""Returns the date object of a birthday that occurs more than once """Returns the date object of a birthday that occurs more than once
in the birthdays list.""" in the birthdays list."""
@ -33,8 +34,10 @@ def getMatch(birthdays):
if birthdayA == birthdayB: if birthdayA == birthdayB:
return birthdayA # Return the matching birthday return birthdayA # Return the matching birthday
# Display the intro: # Display the intro:
print('''Birthday Paradox, by Al Sweigart al@inventwithpython.com print('''Birthday Paradox, by Al Sweigart al@inventwithpython.com
The Birthday Paradox shows us that in a group of N people, the odds The Birthday Paradox shows us that in a group of N people, the odds
that two of them have matching birthdays is surprisingly large. that two of them have matching birthdays is surprisingly large.
This program does a Monte Carlo simulation (that is, repeated random This program does a Monte Carlo simulation (that is, repeated random
@ -42,6 +45,7 @@ simulations) to explore this concept.
(It's not actually a paradox, it's just a surprising result.) (It's not actually a paradox, it's just a surprising result.)
''') ''')
# Set up a tuple of month names in order: # Set up a tuple of month names in order:
MONTHS = ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', MONTHS = ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec') 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec')
@ -62,8 +66,46 @@ for i, birthday in enumerate(birthdays):
# Display a comma for each birthday after the first birthday. # Display a comma for each birthday after the first birthday.
print(', ', end='') print(', ', end='')
monthName = MONTHS[birthday.month - 1] monthName = MONTHS[birthday.month - 1]
dateText = '{} {}'.format(monthName, match.day) dateText = '{} {}'.format(monthName, birthday.day)
print(dateText, end='') print(dateText, end='')
print() print()
print() print()
# Determine if there are two birthdays that match.
match = getMatch(birthdays)
# Display the results:
print('In this simulation, ', end='')
if match != None:
monthName = MONTHS[match.month - 1]
dateText = '{} {}'.format(monthName, match.day)
print('multiple people have a birthday on', dateText)
else:
print('there are no matching birthdays.')
print()
# Run through 100,000 simulations:
print('Generating', numBDays, 'random birthdays 100,000 times...')
input('Press Enter to begin...')
print('Let\'s run another 100,000 simulations.')
simMatch = 0 # How many simulations had matching birthdays in them.
for i in range(100_000):
# Report on the progress every 10,000 simulations:
if i % 1000 == 0:
print(i, 'simulations run...')
birthdays = getBirthdays(numBDays)
if getMatch(birthdays) != None:
simMatch = simMatch + 1
print('100,000 simulations run.')
# Display simulation results:
probability = round(simMatch / 100_000 * 100, 2)
print('Out of 100,000 simulations of', numBDays, 'people, there was a a')
print('matching birthday in that group', simMatch, 'times. This means')
print('that', numBDays, 'people have a', probability, '% chance of')
print('having a matching birthday in their group.')
print('That\'s probably more than you would think!')
#if __name__ == '__main__':