List power

ta_data = [('peter', 'usa', 'cs262'),
			('Andy', 'usa', 'cs212'),
			('Sarah', 'England', 'cs101'),
			('Gundega', 'Latvia', 'cs373'),
			('Job', 'usa', 'cs387'),
			('Sean', 'usa', 'cs253')]

ta_facts = [name + ' lives in ' + country + ' and is the TA for ' +
			course for name, country, course in ta_data]

for row in ta_facts:
	print  row
ta_data = [('peter', 'usa', 'cs262'),
			('Andy', 'usa', 'cs212'),
			('Sarah', 'England', 'cs101'),
			('Gundega', 'Latvia', 'cs373'),
			('Job', 'usa', 'cs387'),
			('Sean', 'usa', 'cs253')]

ta_facts = [name + ' lives in ' + country + ' and is the TA for ' +
			course for name, country, course in ta_data]
remote_ta_facts = [name + ' lives in ' + country + ' and is the TA for ' +
			course for name, country, course in ta_data if country != 'usa']

ta_300 = [name + 'is the TA for ' course for name, country, course in ta_data if course.finde('cs3') != -1]

for row in ta_facts:
	print  row
import itertools

def best_hand(hand):
	return max(itertools.combinations(hand, 5), key=hand_rank)

def test_best_hand():
	assert (sorted(best_hand("6c 7c 8c 9c tc sc js".split()))
		==['6c', '7c', '8c', '9c', 'tc'])
	assert (sorted(best_hand("td tc th 7c 7d 8c 8s".split()))
		==['8c', '8s', 'tc', 'td', 'th'])
	assert (sorted(best_hand("td tc th 7c 7d 7s 7h".split()))
		==['7c', '7d', '7h', '7s', 'td'])
	return 'test_best_hand passes'

print test_best_hand
booge[1].add('red')
booge[1].color='red'
red = 1
houses = [1, 2, 3, 4, 5]
orderings = F(houses)
for(red, green, ivony, yellow, blue) in orderings:

card shuffle

import random

mydeck = [r+s for r in '23456789TJQKA' for s in 'SHDC']

def deal(numhands, n=5, deck=mydeck)
	random.shuffle(deck)
	return [deck[n*i:n*(i+1)] for i in range(numhands)]
def hand_percentages(n=700*1000):
	"sample n random hands and print a table of percentages for each type of hand."
	counts = [0] * 9
	for i in range(n/10):
		for hand in deal(10):
			ranking = hand_rank(hand)[0]
			counts[ranking] += 1
	for i in reversed(range(9)):
		print "%14s: %6.3f %%" % (hand_names[i], 100.*counts[i]/n)
def shuffle1(deck):
	N = len(deck)
	swapped = [False] * N
	while not all(swapped)
		i, j = random.randrange(N), random.randrange(N)
		swapped[i] = swapped[j] = True
		swap(deck, i, j)

def swap(deck, i, j):
	print 'swap', i, j
	deck[i], deck[j] = deck[j], deck[i]
utas = ['Peter', 'Andy', 'Sarah', 'Gundega', 'Job', 'Sean']
uppercasetas = [name.upper() for name in utas]
print uppercasetas

total nums

def ss(nums):
	total = 0
	for i in range(len(nums)):
		total = (total + num[i]**2)
	return total
def ss(nums):
	return sum(x**2 for x in nums)

poker problem set
[‘js’,’jd’,’2s’,’2c’,’7h’]
[(11,’s’),(11,’d’),(2,’s’),(2,’c’),(7,’h’)]

key abs mean absolute value, so -5 would be max nums

def poker(hands):
	"Return the best hand: poker([hand,...]) => hand"
	return max

print max([3, 4, 5, 0]), max([s, 4, -5, 0], key=abs)

highest rank

def poker(hands):
	"Return the best hand: poker([hand,...]) => hand"
	return max(hands, key=hand_rank)

def hand_rank(hand)
	return ???

print max([3, 4, 5, 0]), max([s, 4, -5, 0], key=abs)

Testing

def poker(hands):
    "Return the best hand: poker([hand,...]) => hand"
    return max(hands, key=hand_rank)

def test():
    "Test cases for the functions in poker program"
    sf = "6C 7C 8C 9C TC".split() 
    fk = "9D 9H 9S 9C 7D".split() 
    fh = "TD TC TH 7C 7D".split()
    assert poker([sf, fk, fh]) == sf
    assert poker([fk, fh]) == fk
    assert poker([fh, fh]) == fh
    assert poker([sf]) == sf
    assert poker([sf] + 99*[fh]) == sf
    return 'tests pass'
def hand_rank(hand):
	"Return a value indicating the ranking of a hand"
    ranks = card_ranks(hand)
    if straight(ranks) and flush(hand):            # straight flush
        return (8, max(ranks))
    elif kind(4, ranks):                           # 4 of a kind
        return (7, kind(4, ranks), kind(1, ranks))
    elif kind(3, ranks) and kind(2, ranks):        # full house
        return (6, kind(3, ranks), kind(2, ranks))
    elif flush(hand):                              # flush
        return (5, ranks)
    elif straight(ranks):                          # straight
        return (4, max(ranks))
    elif kind(3, ranks):                           # 3 of a kind
        return (3, kind(3, ranks), ranks)
    elif two_pair(ranks):                          # 2 pair
        return (2, two_pair(ranks), ranks)
    elif kind(2, ranks):                           # kind
        return (1, kind(2, ranks), ranks)
    else:                                          # high card
        return (0, ranks)
def poker(hands):
    "Return the best hand: poker([hand,...]) => hand"
    return allmax(hands, key=hand_rank)

def allmax(iterable, key=None):
	"Return a list of all items equal to the max of the iterable."
	result, maxval = [], None
	key = key or (lambda x: x)
	for x in iterable:
		xval = key(x)
		if not result or xval > maxval:
			result, maxval = [x], xval
		elif xval == maxval:
			result.append(x)
	return result

def hand_rank(hand):
	"Return a value indicating the ranking of a hand"
    ranks = card_ranks(hand)
    if straight(ranks) and flush(hand):            # straight flush
        return (8, max(ranks))
    elif kind(4, ranks):                           # 4 of a kind
        return (7, kind(4, ranks), kind(1, ranks))
    elif kind(3, ranks) and kind(2, ranks):        # full house
        return (6, kind(3, ranks), kind(2, ranks))
    elif flush(hand):                              # flush
        return (5, ranks)
    elif straight(ranks):                          # straight
        return (4, max(ranks))
    elif kind(3, ranks):                           # 3 of a kind
        return (3, kind(3, ranks), ranks)
    elif two_pair(ranks):                          # 2 pair
        return (2, two_pair(ranks), ranks)
    elif kind(2, ranks):                           # kind
        return (1, kind(2, ranks), ranks)
    else:                                          # high card
        return (0, ranks)

def card_ranks(cards):
    "Return a list of the ranks, sorted with higher first."
    ranks = ['--23456789TJQKA'.index(r) for r,s in cards]
    ranks.sort(reverse=True)
    return [5, 4, 3, 2, 1] if (ranks == [14, 5, 4, 3, 2])

def straight(ranks):
	"Return True if the ordered ranks form a 5-card straight."
	return (max(ranks)-min(ranks) == 4) and len(set(ranks)) == 5

def flush(hand):
	"Return True if all the cards have the same suit."
	suits = [s for r, s in hand]
	return len(set(suits)) == 1

def kind(n, ranks):
	"""Return the first rank that this hand has exactly n of.
	Return None if there is no n-of-a-kind in the hand."""
	for r in ranks:
		if ranks.count(r) == n: return r
	return None

def two_pair(ranks):
	"""If there are two pair, return the two ranks as a
	tuple: (highest, lowest); otherwise return None."""
	pair = kind(2, ranks)
	lowpair = kind(2, list(reversed(ranks)))
	if pair and lowpair != pair:
		return (pair, lowpair)
	else:
		return None

def test():
    "Test cases for the functions in poker program"
    sf = "6C 7C 8C 9C TC".split() # Straight Flush
    fk = "9D 9H 9S 9C 7D".split() # Four of a Kind
    fh = "TD TC TH 7C 7D".split() # Full House
    tp = "5S 5D 9H 9C 6S".split() # two pair
    s1 = "AS 2S 3S 4S 5C".split() # A-5 straight
    s2 = "2C 3C 4C 5S 6S".split() # 2-6 straight
    ah = "AS 2S 3S 4S 6C".split() # A high
    sh = "2S 3S 4S 6C 7D".split() # 7 high
    assert poker([s1, s2, ah, sh]) == s2
    fkranks = card_ranks(fk)
    tpranks = card_ranks(tp)
    assert kind(4, fkranks) == 9
    assert kind(3, fkranks) == None
    assert kind(2, fkranks) == None
    assert kind(1, fkranks) == 7
    assert two_pair(fkranks) == None
    assert two_pair(tpranks) == (9, 5)
    assert straight([9, 8, 7, 6, 5]) == True
    assert straight([9, 8, 8, 6, 5]) == False
    assert flush(sf) == True
    assert flush(fk) == False
    assert card_ranks(sf) == [10, 9, 8, 7, 6]
    assert card_ranks(fk) == [9, 9, 9, 9, 7]
    assert card_ranks(fh) == [10, 10, 10, 7, 7]
    assert poker([sf, fk, fh]) == sf
    assert poker([fk, fh]) == fk
    assert poker([fh, fh]) == fh
    assert poker([sf]) == sf
    assert poker([sf] + 99*[fh]) == sf
    assert hand_rank(sf) == (8, 10)
    assert hand_rank(fk) == (7, 9, 7)
    assert hand_rank(fh) == (6, 10, 7)
    return 'tests pass'

Dynamic slice

import sys

def remove_html_markup(s):
	tag = False
	quote = False
	out = ""

	for c in s:
		if c == '<' and not quote:
			tag = True
		elif c == '>' and not quote:
			tag = False
		elif (c == '"' or c == "'") and tag:
			quote = not quote
		elif not tag:
			out = out + c

	return out

def traceit(frame, event, arg):
	if event == "line":
		filename = frame.f_code.co_filename
		lineno = frame.f_lineno
		print filename, lineno

	return traceit

sys.settrace(traceit)
void bug(){
	int x;
	assert x == 0;
}
resume = True
while resume:
	command = input_command()
	process(command)

command_index = 0

def input_command():

	commands = ["open", "save", "quit"]
	global command_index
	command = commands[command_index]
	command_index = command_index + 1
	return command

saved_commands = []
def input_command():
	command = original_input_command()
	return command

def process(command):
	global resume
	print repr(command)

	if command.startswitch('g'):
		resume = False

while resume:
	command = input_command()
	process(command)

zip

class ZIPCode:
	def __init__(self, zip):
		self._zip = zip
		self.checkRep()

	def zip(self):
		return self._zip()

	def checkRep(self):
		assert len(self.zip()) == 5
		for i in range(0, 5):
			assert '0' <= self.zip()[i] <= '9'
import re

def test(s):

	if re.search("]*>", s) >= 0:
		return "FAIL"
	else
		return "PASS"

def ddmin(s):
	assert test(s) == "FAIL"

	n = 2
	while len(s) >= 2:
		start = 0
		subset_length = len(s) / n
		some_complement_is_failing = False

		while start < len(s):
			compleent = s[:start] + [start + subset_length:]
			if test(complement) == "FAIL":
				s = complement
				n = max(n - 1, 2)
				some_complement_is_failing = True
				break

			start = start + subset_length

		if not some_complement_is_failing:
			n = min( n * 2, len(s))
			if n == len(s):
				break

	return s
import random

def fuzzer():
	string_length = int(random.random() * 1024)
	out = ""
	for i in range(0, string_length):
		c = chr(int(random.random() * 96 + 32))
		out = out + c

	return out
print fuzzer()
patches = [1, 2, 3, 4, 5, 6, 7, 8]

def test(s):
	print repr(s), len(s),
	if 3 in s and 6 in s:
		print "FAIL"
		return "FAIL"
	else:
		print "PASS"
		return "PASS"

print ddmin(patches, test)

Debugging

def debug(command, my_arg, my_locals):
	global stepping
	global breakpoints

	if command.find(' ') > 0:
		arg = command.split(' ')[1]
	else:
		arg = None

	if command.startswith('s'):
		stepping = True
		return True

def traceit(frame, event, arg):
	global stepping
	global breakpoints

	if event == 'Line':
		if stepping or breaking.has_key(frame.f_lineno):
			resume = False
			while not resume:
				print event, frame.f_lineno, frame.f_code.co_name, frame.f_locals
				command = input_command()
				resume = debug(command, arg, frame.f_locals)
		return traceit

Assertions is the most powerful debugging tool, automating debugging tool.

def test_square_root():
	assert square_root(4) == 2
	assert square_root(g) == 3
	# and so on
import math

def square_root(x):
	assert x >= 0
	y = math.sqrt(x)
	assert y * y == x
	return y

testing square root

import math
random

def square_root(x):
	assert x >= 0
	y = math.sqrt(x)
	assert y * y == x
	return y

for i in range(1, 1000):
	r = random.random() * 10000
	try:
		z = square_root(r)
	except:
		print r, math.sqrt(r) * math.sqrt(r)
		break

print "Done!"
import math
import random

def square_root(x, eps=10e-7):
    assert x >= 0
    y = math.sqrt(x)
    assert abs(y * y - x) < eps
    return y

for i in range(1, 1000):
    r = random.random() * 1000
    z = square_root(r)

print "Done!"
class Time:
	def __init__(self, h = 0, m = 0, s = 0):
		self._hours = h
		self._minutes = m
		self._seconds = s

	def hours(self):
		return self._hours

	def minutes(self):
		return self._minutes

	def seconds(self):
		return self._seconds

	def __repr__(self):
		return "{:2d}{:2d}{:2d}".format(
			self.hours(), self.minutes(), self.seconds())

t = Time(13, 0, 0)
print t

parsing tree

hello my luft ballons
[(“word-element”, “hello”),
(“word-element”,”my”),
(“javascript-element”), “document.write(99);”)
(“word-elment”, “luftballons”),
]

def interpret(trees):
	for tree in trees:
		treetype = tree[0]
		if treetype == "word-element":
			graphics.word(node[1])
		elif treetype == "javascript-element":
			jstext = tree[1]
			jslexer = lex.lex(module=jstokens)
			jsparser = yacc.yacc(module=jsgrammar)
			jstree = jsparser.parse(jstext,lexer=jslexer)
			result = jsinterp.interpret( jstree )
			graphics.word( result )
def env_lookup(vname, env):
	if vname in env[1]:
		return (env[1])[vname]
	elif env[0] == None:
		return None
	else:
		return env_lookup(vname, env[0])
var a = 1;
function mistletue(baldr){
	baldr = baldr + 1;
	a = a + 2;
	baldr = baldr + a;
	return baldr;
}
write (mistletue(5));
def optimize(tree):
	etype = tree[0]
	if etype == "binop":
		a = tree[1]
		op = tree[2]
		b = tree[3]
		if op == "*" and b == ("number","1"):
			return a
		return tree
def remove_html_markup(s):
	tag = False
	out = ""

	for c in s:
		if c == '<':
			tag = True
		elif c == '>':
			tag = False
		elif not tag:
			out = out + c

	return out
print remove_html_markup("<b>foo</b>")

fibo

def fibo(n):
	in n <= 2:
		return 1
	else:
		return fibo(n-1)+fibo(n-2)

print fibo(20)
&#91;/python&#93;

&#91;python&#93;
chart = {}

def memofibo(n):
    if n in chart:
    	return chart&#91;n&#93;
    elif n <= 2:
    	chart&#91;n&#93; = 1
    
print memofibo(24)
&#91;/python&#93;

&#91;python&#93;
def t_javascript(token):
	r'<script\ type=\"text\/javascript\"\>'
	token.lexer.code_start = token.lexer.lexpos
	token.lexer.begin("javascript")

def t_javascript_end(token):
def t_javascript(token):
	r'<script\ type=\"text\/javascript\"\>'
	token.lexer.code_start = token.lexer.lexpos
	token.lexer.begin("javascript")

def t_javascript_end(token):
	r'\<\/script\>'
	token.value = token.lexer.lexdata[token.lexer.code_start:
		token.lexer.lexpos-9]
	token.type = 'JAVASCRIPT'
	token.lexer.lineno += token.value.count('\n')
	token.lexer.begin.('INITIAL')
	return token

parthing:構文解析 lexing:字句解析
after regular expression, lexer get token value.

javascript to python

#        function mymin(a, b){
#            if (a < b){
#                return a;
#            } else {
#                return b;
#            };
#        }
#        
#        function square(x){
#            return x * x;
#        }
#        
#        write(mymin(square(-2), square(3)));

def mymin(a, b):
	if (a < b):
		return a
	else:
		return b

def square(x):
	return x * x
print mymin(square(-2), square(3))
[1,2,3,4,5,6,7]

def odds_only(numbers):
	for N in numbers:
		if N % 2 == 1:
			yield N
def small_words(words):
	for word in words:
		if len(word) <= 3:
			yield word

print [w for w in small_words(["The","quick","brown","fox"])]
grammar = [
	("exp",["exp","+","exp"]),
	("exp",["exp","-","exp"]),
	("exp",["(","exp",")"]),
	("exp",["num"]),
]

def expand(tokens, grammar):
	for pos in range(len(tokens)):
		for rule in grammar:

depth = 1
utterances = [["exp"]]
def sublists(big_list, selected_so_far):
	if big_list == []:
		print selected_so_far
	else:
		current_element = big_list[0]
		rest_of_big_list = big_list[1:]
		sublists(rest_of_big_list, selected_so_far + [current_element])
		sublists(rest_of_big_list, selected_so_far )

	dinner_guests = ["LM", "ECS", "SBA"]
	sublists(dinner_guests, [])
def cfgempty(grammar, symbol, visited):
	if symbol in visited:
		return None
	elif not any([rule[0] == symbol for rule in grammar ]):
		return [symbol]
	else:
		new_visited = visited + [symbol]
		for rhs in [r[1] for r in grammar if r[0] == symbol]:
			if all([None] != cfgempty(frammar, r, new_visited) for r in rhs):
				result = []
				for r in rhs:
					result = result + cfgempty(grammar, r, new_visited)
				return result
		return None

JS Number

tokens = (
	'IDENTIFIER',
	'NUMBER',
	'STRING'
	)

def t_NUMBER(t):
	r'-?[0-9]+(?:\.[0-9]*)?'
	t.value = float(t.value)
	return t

def t_STRING(t):
	r'([^"\\]|(\\.))*"'
	t.value = t.value[1:-1]
	return t
function gcd(a,b){
	if(a==b){
		return a;
	} else {
		if(a > b){
		return gcd(a-b, b);
		} else {
			return gcd(a, b- a)
		}
	}
}

recursion: function call itself

javascript and python

def uptoten(x):
if x < 10: return x else: return 10 javascriptcode=""" function uptoten(x) { if x < 10 { return x } else { return 10 } } """ [/python]