SimplePrograms (original) (raw)

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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 (f'Hi, {name}.')

3 lines: For loop, built-in enumerate function

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

4 lines: Fibonacci, tuple assignment

parents, babies = (1, 1) while babies < 100: print (f'This generation has {babies} 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 (f'I owe the grocer ${grocery_bill:.2f}')

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, from..import

indent your Python code to put into an email

from pathlib import Path

python_files = Path().glob('*.py') for file_name in sorted(python_files): print (f' ------{file_name}')

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

print()

10 lines: Time, conditionals, 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 = ''' {} bottles of beer on the wall, {} bottles of beer, take one down, pass it around, {} bottles of beer on the wall! ''' bottles_of_beer = 9 while bottles_of_beer > 1: print (REFRAIN.format(bottles_of_beer, bottles_of_beer, bottles_of_beer - 1)) bottles_of_beer -= 1

12 lines: Classes

class BankAccount: 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

def cmp(a, b): '''Return -1 if a < b, 0 if a == b, 1 if 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') 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 (f'{name} is {status} ({float(pct):.2f})')

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 = '''

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))

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