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| Here are some example simple programs. Please feel free to contribute, but see notice at bottom, please. These examples assume version 2.4 or above of Python. You should be able to run them simply by copying/pasting the code into a file and running Python. Or by inserting this line (#!/usr/bin/env python) at the beginning of your file (Unix/Linux), making the file executable (chmod u+x filename.py) and running it (./filename.py). ------ 1 line: Output {{{#!python numbers=disable print 'Hello, world!' }}} ------ 2 lines: Input, assignment {{{#!python numbers=disable name = raw_input('What is your name?\n') print 'Hi, %s.' % (name) }}} ------ 3 lines: For loop, built-in enumerate function {{{#!python numbers=disable my_list = ['john', 'pat', 'gary', 'michael'] for i, name in enumerate(my_list): print "iteration %i is %s" % (i, name) }}} ------ 4 lines: Fibonacci, tuple assignment {{{#!python numbers=disable parents, babies = (1, 1) while babies < 100: print 'This generation has %d babies' % babies parents, babies = (babies, parents + babies) }}} ------ 5 lines: Functions {{{#!python numbers=disable def greet(name): print 'hello', name greet('Jack') greet('Jill') greet('Bob') }}} ------ 6 lines: Import, regular expressions {{{#!python numbers=disable import re for test_string in ['555-1212', 'ILL-EGAL']: if re.match(r'^\d{3}-\d{4}$', test_string): print test_string, 'is a valid US local phone number' else: print test_string, 'rejected' }}} ------ 7 lines: Dictionaries, generator expressions {{{#!python numbers=disable prices = {'apple': 0.40, 'banana': 0.50} my_purchase = { 'apple': 1, 'banana': 6} grocery_bill = sum(prices[fruit] * my_purchase[fruit] for fruit in my_purchase) print 'I owe the grocer $%.2f' % grocery_bill }}} ------ 8 lines: Command line arguments, exception handling {{{#!python numbers=disable #!/usr/bin/env python # This program adds up integers in the command line import sys try: total = sum(int(arg) for arg in sys.argv[1:]) print 'sum =', total except ValueError: print 'Please supply integer arguments' }}} ------ 9 lines: Opening files {{{#!python numbers=disable # indent your Python code to put into an email import glob # glob supports Unix style pathname extensions python_files = glob.glob('*.py') for fn in sorted(python_files): print ' ------', fn for line in open(fn): print ' ' + line.rstrip() }}} ------ 10 lines: Time, conditionals {{{#!python numbers=disable import time now = time.localtime() hour = now.tm_hour if hour < 8: print 'sleeping' elif hour < 9: print 'commuting' elif hour < 17: print 'working' elif hour < 18: print 'commuting' elif hour < 20: print 'eating' elif hour < 22: print 'resting' else: print 'sleeping' }}} ------ 11 lines: Triple-quoted strings, while loop {{{#!python numbers=disable REFRAIN = ''' %d bottles of beer on the wall, %d bottles of beer, take one down, pass it around, %d bottles of beer on the wall! ''' bottles_of_beer = 99 while bottles_of_beer > 1: print REFRAIN % (bottles_of_beer, bottles_of_beer, bottles_of_beer - 1) bottles_of_beer -= 1 }}} ------ 12 lines: Classes {{{#!python numbers=disable class BankAccount(object): def __init__(self, initial_balance=0): self.balance = initial_balance def deposit(self, amount): self.balance += amount def withdraw(self, amount): self.balance -= amount def overdrawn(self): return self.balance < 0 my_account = BankAccount(15) my_account.withdraw(5) print my_account.balance }}} ------ 13 lines: Unit testing with unittest {{{#!python numbers=disable import unittest def median(pool): copy = sorted(pool) size = len(copy) if size % 2 == 1: return copy[(size - 1) / 2] else: return (copy[size/2 - 1] + copy[size/2]) / 2 class TestMedian(unittest.TestCase): def testMedian(self): self.failUnlessEqual(median([2, 9, 9, 7, 9, 2, 4, 5, 8]), 7) if __name__ == '__main__': unittest.main() }}} ------ 14 lines: Doctest-based testing {{{#!python numbers=disable def median(pool): '''Statistical median to demonstrate doctest. >>> median([2, 9, 9, 7, 9, 2, 4, 5, 8]) 7 ''' copy = sorted(pool) size = len(copy) if size % 2 == 1: return copy[(size - 1) / 2] else: return (copy[size/2 - 1] + copy[size/2]) / 2 if __name__ == '__main__': import doctest doctest.testmod() }}} ------ 15 lines: itertools {{{#!python numbers=disable import itertools lines = ''' This is the first paragraph. This is the second. '''.splitlines() # Use itertools.groupby and bool to return groups of # consecutive lines that either have content or don't. for has_chars, frags in itertools.groupby(lines, bool): if has_chars: print ' '.join(frags) # PRINTS: # This is the first paragraph. # This is the second. }}} ------ 16 lines: csv module, tuple unpacking, cmp() built-in {{{#!python numbers=disable import csv # write stocks data as comma-separated values writer = csv.writer(open('stocks.csv', 'wb', buffering=0)) writer.writerows([ ('GOOG', 'Google, Inc.', 505.24, 0.47, 0.09), ('YHOO', 'Yahoo! Inc.', 27.38, 0.33, 1.22), ('CNET', 'CNET Networks, Inc.', 8.62, -0.13, -1.49) ]) # read stocks data, print status messages stocks = csv.reader(open('stocks.csv', 'rb')) status_labels = {-1: 'down', 0: 'unchanged', 1: 'up'} for ticker, name, price, change, pct in stocks: status = status_labels[cmp(float(change), 0.0)] print '%s is %s (%s%%)' % (name, status, pct) }}} ------ 18 lines: 8-Queens Problem (recursion) {{{#!python numbers=disable BOARD_SIZE = 8 def under_attack(col, queens): left = right = col for r, c in reversed(queens): left, right = left-1, right+1 if c in (left, col, right): return True return False def solve(n): if n == 0: return [[]] smaller_solutions = solve(n-1) return [solution+[(n,i+1)] for i in range(BOARD_SIZE) for solution in smaller_solutions if not under_attack(i+1, solution)] for answer in solve(BOARD_SIZE): print answer }}} ------ 20 lines: Prime numbers sieve w/fancy generators {{{#!python numbers=disable import itertools def iter_primes(): # an iterator of all numbers between 2 and +infinity numbers = itertools.count(2) # generate primes forever while True: # get the first number from the iterator (always a prime) prime = numbers.next() yield prime # this code iteratively builds up a chain of # filters...slightly tricky, but ponder it a bit numbers = itertools.ifilter(prime.__rmod__, numbers) for p in iter_primes(): if p > 1000: break print p }}} ------ 21 lines: XML/HTML parsing (using Python 2.5 or third-party library) {{{#!python numbers=disable dinner_recipe = '''<html><body><table> <tr><th>amt</th><th>unit</th><th>item</th></tr> <tr><td>24</td><td>slices</td><td>baguette</td></tr> <tr><td>2+</td><td>tbsp</td><td>olive oil</td></tr> <tr><td>1</td><td>cup</td><td>tomatoes</td></tr> <tr><td>1</td><td>jar</td><td>pesto</td></tr> </table></body></html>''' # In Python 2.5 or from http://effbot.org/zone/element-index.htm import xml.etree.ElementTree as etree tree = etree.fromstring(dinner_recipe) # For invalid HTML use http://effbot.org/zone/element-soup.htm # import ElementSoup, StringIO # tree = ElementSoup.parse(StringIO.StringIO(dinner_recipe)) pantry = set(['olive oil', 'pesto']) for ingredient in tree.getiterator('tr'): amt, unit, item = ingredient if item.tag == "td" and item.text not in pantry: print "%s: %s %s" % (item.text, amt.text, unit.text) }}} ------ 28 lines: 8-Queens Problem (define your own exceptions) {{{#!python numbers=disable BOARD_SIZE = 8 class BailOut(Exception): pass def validate(queens): left = right = col = queens[-1] for r in reversed(queens[:-1]): left, right = left-1, right+1 if r in (left, col, right): raise BailOut def add_queen(queens): for i in range(BOARD_SIZE): test_queens = queens + [i] try: validate(test_queens) if len(test_queens) == BOARD_SIZE: return test_queens else: return add_queen(test_queens) except BailOut: pass raise BailOut queens = add_queen([]) print queens print "\n".join(". "*q + "Q " + ". "*(BOARD_SIZE-q-1) for q in queens) }}} ------ 33 lines: "Guess the Number" Game from http://inventwithpython.com {{{#!python numbers=disable import random guessesTaken = 0 print 'Hello! What is your name?' myName = raw_input() number = random.randint(1, 20) print 'Well, ' + myName + ', I am thinking of a number between 1 and 20.' while guessesTaken < 6: print 'Take a guess.' guess = input() #fyi: input() is for numbers. raw_input() is for strings. guessesTaken = guessesTaken + 1 if guess < number: print 'Your guess is too low.' if guess > number: print 'Your guess is too high.' if guess == number: break if guess == number: guessesTaken = str(guessesTaken) print 'Good job, ' + myName + '! You guessed my number in ' + guessesTaken + ' guesses!' if guess != number: print 'Nope. The number I was thinking of was ' + str(number) }}} ------ Hi, I started this page in May 2007, and I provided the first 10+ or so examples (which may have changed since then). -- SteveHowell All code on this page is open source, of course, with the standard Python license. Minor cleanups are welcome, but if you want to do major restructuring of this page, please run them by the folks on the Python mailing list, or if you are impatient for a response, please just make your own copy of this page. Thanks, and I hope this code is useful for you! Some goals for this page: 1. All examples should be simple. 2. There should be a gentle progression through Python concepts. ---- CategoryDocumentation |
i am a faggot |
i am a faggot