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## page was renamed from SimplePrograms = Semplici Programmi versione Italiana
## page was renamed from SimplePrograms

Here are some example simple programs. Please feel free to contribute, but see notice at bottom, please.

These examples assume version 2.6 or above of Python.
You should be able to run them simply by copying/pasting the code into a file (named for example test.py) and running python test.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, new style formatting
{{{#!python numbers=disable
The examples below will increase in number of lines of code and difficulty:

1 line: Output

{{{
print ('Hello, world!')
}}}
----
2 lines: Input, assignment

{{{
name = input('What is your name?\n')
print ('Hi, %s.' % name)
}}}
----
3 lines: For loop, built-in enumerate function, new style formatting

{{{
Line 24: Line 21:
    print "iteration {iteration} is {name}".format(iteration=i, name=name)
}}}

    
------ 4 lines: Fibonacci, tuple assignment
{{{#!python numbers=disable
    print ("iteration {iteration} is {name}".format(iteration=i, name=name))
}}}
----
4 lines: Fibonacci, tuple assignment

{{{
Line 31: Line 29:
    print 'This generation has {0} babies'.format(babies)     print ('This generation has {0} babies'.format(babies))
Line 34: Line 32:

    
------ 5 lines: Functions
{{{#!python numbers=disable
----
5 lines: Functions

{{{
Line 38: Line 37:
    print 'Hello', name     print ('Hello', name)
Line 43: Line 43:

    
------ 6 lines: Import, regular expressions
{{{#!python numbers=disable
----
6 lines: Import, regular expressions

{{{
Line 49: Line 50:
        print test_string, 'is a valid US local phone number'         print (test_string, 'is a valid US local phone number')
Line 51: Line 52:
        print test_string, 'rejected'
}}}

    
------ 7 lines: Dictionaries, generator expressions
{{{#!python numbers=disable
        print (test_string, 'rejected')
}}}
----
7 lines: Dictionaries, generator expressions

{{{
Line 62: Line 64:
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
print ('I owe the grocer $%.2f' % grocery_bill)
}}}
----
8 lines: Command line arguments, exception handling

{{{
# This program adds up integers that have been passed as arguments in the command line
Line 73: Line 74:
    print 'sum =', total     print ('sum =', total)
Line 75: Line 76:
    print 'Please supply integer arguments'
}}}


    
------ 9 lines: Opening files
{{{#!python numbers=disable
    print ('Please supply integer arguments')
}}}
----
9 lines: Opening files

{{{
Line 86: Line 87:
    print ' ------' + file_name     print (' ------' + file_name)
Line 90: Line 91:
            print ' ' + line.rstrip()

    print
}}}

    
------ 10 lines: Time, conditionals, from..import, for..else
{{{#!python numbers=disable
            print (' ' + line.rstrip())

    print()
}}}
----
10 lines: Time, conditionals, from..import, for..else

{{{
Line 111: Line 113:
        print activities[activity_time]         print (activities[activity_time])
Line 114: Line 116:
    print 'Unknown, AFK or sleeping!'
}}}

    
------ 11 lines: Triple-quoted strings, while loop
{{{#!python numbers=disable
    print ('Unknown, AFK or sleeping!')
}}}
----
11 lines: Triple-quoted strings, while loop

{{{
Line 125: Line 128:
bottles_of_beer = 99 bottles_of_beer = 9
Line 127: Line 130:
    print REFRAIN % (bottles_of_beer, bottles_of_beer,
        bottles_of_beer - 1)
    print (REFRAIN % (bottles_of_beer, bottles_of_beer,
        bottles_of_beer - 1))
Line 131: Line 134:

   
------ 12 lines: Classes
{{{#!python numbers=disable
----
12 lines: Classes

{{{
Line 144: Line 148:
my_account.withdraw(5)
print my_account.balance
}}}

    
------ 13 lines: Unit testing with unittest
{{{#!python numbers=disable
my_account.withdraw(50)
print (my_account.balance, my_account.overdrawn())
}}}
----
13 lines: Unit testing with unittest

{{{
Line 155: Line 160:
        return copy[(size - 1) / 2]         return copy[int((size - 1) / 2)]
Line 157: Line 162:
        return (copy[size/2 - 1] + copy[size/2]) / 2         return (copy[int(size/2 - 1)] + copy[int(size/2)]) / 2
Line 160: Line 165:
        self.failUnlessEqual(median([2, 9, 9, 7, 9, 2, 4, 5, 8]), 7)         self.assertEqual(median([2, 9, 9, 7, 9, 2, 4, 5, 8]), 7)
Line 164: Line 169:


    
------ 14 lines: Doctest-based testing
{{{#!python numbers=disable
----
14 lines: Doctest-based testing

{{{
Line 171: Line 176:
    7     6 #change to 7 in order to pass the test
Line 176: Line 181:
        return copy[(size - 1) / 2]         return copy[int((size - 1) / 2)]
Line 178: Line 183:
        return (copy[size/2 - 1] + copy[size/2]) / 2         return (copy[int(size/2 - 1)] + copy[int(size/2)]) / 2
Line 183: Line 188:

    
------ 15 lines: itertools
{{{#!python numbers=disable
----
15 lines: itertools

{{{
Line 197: Line 203:
        print ' '.join(frags)         print (' '.join(frags))
Line 202: Line 208:

    
------ 16 lines: csv module, tuple unpacking, cmp() built-in
{{{#!python numbers=disable
----
16 lines: csv module, tuple unpacking, cmp() built-in

{{{
Line 207: Line 214:
# need to define cmp function in Python 3
def cmp(a, b):
    return (a > b) - (a < b)
Line 208: Line 219:
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)
])
with open('stocks.csv', 'w', newline='') as stocksFileW:
    writer =
csv.writer(stocksFileW)
    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, -1.4901]
    ]
)
Line 216: Line 228:
stocks = csv.reader(open('stocks.csv', 'rb'))
status_lab
els = {-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
with open('stocks.csv', 'r') as stocksFile:
    
stocks = csv.reader(stocksFile)

    status_la
bels = {-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 (%.2f)' % (name, status, float(pct)))
}}}
----
18 lines: 8-Queens Problem (recursion)

{{{
Line 243: Line 259:
        for i in xrange(BOARD_SIZE)         for i in range(BOARD_SIZE)
Line 247: Line 263:
    print answer
}}}

    
------ 20 lines: Prime numbers sieve w/fancy generators
{{{#!python numbers=disable
    print (answer)
}}}
----
20 lines: Prime numbers sieve w/fancy generators

{{{
Line 261: Line 278:
         prime = numbers.next()          prime = next(numbers)
Line 266: Line 283:
         numbers = itertools.ifilter(prime.__rmod__, numbers)          numbers = filter(prime.__rmod__, numbers)
Line 271: Line 288:
    print p
}}}

    
------ 21 lines: XML/HTML parsing (using Python 2.5 or third-party library)
{{{#!python numbers=disable
    print (p)
}}}
----
21 lines: XML/HTML parsing

{{{
Line 284: Line 302:
# In Python 2.5 or from http://effbot.org/zone/element-index.htm # From http://effbot.org/zone/element-index.htm
Line 296: Line 314:
        print "%s: %s %s" % (item.text, amt.text, unit.text)
}}}

    
------ 28 lines: 8-Queens Problem (define your own exceptions)
{{{#!python numbers=disable
        print ("%s: %s %s" % (item.text, amt.text, unit.text))
}}}
----
28 lines: 8-Queens Problem (define your own exceptions)

{{{
Line 327: Line 346:
print queens
print "\n".join(". "*q + "Q " + ". "*(BOARD_SIZE-q-1) for q in queens)

}}}

    
------ 33 lines: "Guess the Number" Game (edited) from http://inventwithpython.com
{{{#!python numbers=disable
print (queens)
print ("\n".join(". "*q + "Q " + ". "*(BOARD_SIZE-q-1) for q in queens))
}}}
----
33 lines: "Guess the Number" Game (edited) from http://inventwithpython.com

{{{
Line 338: Line 357:
name = raw_input('Hello! What is your name?\n') name = input('Hello! What is your name?\n')
Line 341: Line 360:
print 'Well, {0}, I am thinking of a number between 1 and 20.'.format(name) print ('Well, {0}, I am thinking of a number between 1 and 20.'.format(name))
Line 345: Line 364:
    guess = int(raw_input('Take a guess: '))     guess = int(input('Take a guess: '))
Line 350: Line 369:
        print 'Your guess is too low.'         print ('Your guess is too low.')
Line 353: Line 372:
        print 'Your guess is too high.'         print ('Your guess is too high.')
Line 359: Line 378:
    print 'Good job, {0}! You guessed my number in {1} guesses!'.format(name, guesses_made)     print ('Good job, {0}! You guessed my number in {1} guesses!'.format(name, guesses_made))
Line 361: Line 380:
    print 'Nope. The number I was thinking of was {0}'.format(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.
    print ('Nope. The number I was thinking of was {0}'.format(number))
}}}

----
These all run under Python 3. If you are interested in differences between Python 2 and Python 3, please take a look at the [[https://wiki.python.org/moin/SimplePrograms?action=recall&rev=154|previous version of this page]].

The examples below will increase in number of lines of code and difficulty:

1 line: Output

print ('Hello, world!')


2 lines: Input, assignment

name = input('What is your name?\n')
print ('Hi, %s.' % name)


3 lines: For loop, built-in enumerate function, new style formatting

friends = ['john', 'pat', 'gary', 'michael']
for i, name in enumerate(friends):
    print ("iteration {iteration} is {name}".format(iteration=i, name=name))


4 lines: Fibonacci, tuple assignment

parents, babies = (1, 1)
while babies < 100:
    print ('This generation has {0} babies'.format(babies))
    parents, babies = (babies, parents + babies)


5 lines: Functions

def greet(name):
    print ('Hello', name)

greet('Jack')
greet('Jill')
greet('Bob')


6 lines: Import, regular expressions

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

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

# This program adds up integers that have been passed as arguments 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

# indent your Python code to put into an email
import glob
# glob supports Unix style pathname extensions
python_files = glob.glob('*.py')
for file_name in sorted(python_files):
    print ('    ------' + file_name)

    with open(file_name) as f:
        for line in f:
            print ('    ' + line.rstrip())

    print()


10 lines: Time, conditionals, from..import, for..else

from time import localtime

activities = {8: 'Sleeping',
              9: 'Commuting',
              17: 'Working',
              18: 'Commuting',
              20: 'Eating',
              22: 'Resting' }

time_now = localtime()
hour = time_now.tm_hour

for activity_time in sorted(activities.keys()):
    if hour < activity_time:
        print (activities[activity_time])
        break
else:
    print ('Unknown, AFK or sleeping!')


11 lines: Triple-quoted strings, while loop

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 = 9
while bottles_of_beer > 1:
    print (REFRAIN % (bottles_of_beer, bottles_of_beer,
        bottles_of_beer - 1))
    bottles_of_beer -= 1


12 lines: Classes

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(50)
print (my_account.balance, my_account.overdrawn())


13 lines: Unit testing with unittest

import unittest
def median(pool):
    copy = sorted(pool)
    size = len(copy)
    if size % 2 == 1:
        return copy[int((size - 1) / 2)]
    else:
        return (copy[int(size/2 - 1)] + copy[int(size/2)]) / 2
class TestMedian(unittest.TestCase):
    def testMedian(self):
        self.assertEqual(median([2, 9, 9, 7, 9, 2, 4, 5, 8]), 7)
if __name__ == '__main__':
    unittest.main()


14 lines: Doctest-based testing

def median(pool):
    '''Statistical median to demonstrate doctest.
    >>> median([2, 9, 9, 7, 9, 2, 4, 5, 8])
    6 #change to 7 in order to pass the test
    '''
    copy = sorted(pool)
    size = len(copy)
    if size % 2 == 1:
        return copy[int((size - 1) / 2)]
    else:
        return (copy[int(size/2 - 1)] + copy[int(size/2)]) / 2
if __name__ == '__main__':
    import doctest
    doctest.testmod()


15 lines: itertools

from itertools import groupby
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 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

import csv

# need to define cmp function in Python 3
def cmp(a, b):
    return (a > b) - (a < b)

# write stocks data as comma-separated values
with open('stocks.csv', 'w', newline='') as stocksFileW:
    writer = csv.writer(stocksFileW)
    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, -1.4901]
    ])

# read stocks data, print status messages
with open('stocks.csv', 'r') as stocksFile:
    stocks = csv.reader(stocksFile)

    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 (%.2f)' % (name, status, float(pct)))


18 lines: 8-Queens Problem (recursion)

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

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 = next(numbers)
         yield prime

         # this code iteratively builds up a chain of
         # filters...slightly tricky, but ponder it a bit
         numbers = filter(prime.__rmod__, numbers)

for p in iter_primes():
    if p > 1000:
        break
    print (p)


21 lines: XML/HTML parsing

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>'''

# 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)

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 (edited) from http://inventwithpython.com

import random

guesses_made = 0

name = input('Hello! What is your name?\n')

number = random.randint(1, 20)
print ('Well, {0}, I am thinking of a number between 1 and 20.'.format(name))

while guesses_made < 6:

    guess = int(input('Take a guess: '))

    guesses_made += 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:
    print ('Good job, {0}! You guessed my number in {1} guesses!'.format(name, guesses_made))
else:
    print ('Nope. The number I was thinking of was {0}'.format(number))


These all run under Python 3. If you are interested in differences between Python 2 and Python 3, please take a look at the previous version of this page.


CategoryDocumentation

SimplePrograms (last edited 2019-11-09 23:29:53 by FrancesHocutt)

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