Think Python/Answers - Wikibooks, open books for an open world (2024)

• 1 Chapter 1
  • 1.1 Exercise 1.2
• 2 Chapter 2
  • 2.1 Exercise 2.1
  • 2.2 Exercise 2.2
• 3 Chapter 3
  • 3.1 Exercise 3.1
  • 3.2 Exercise 3.3
• 4 Chapter 4
  • 4.1 4.3 Exercise 1
  • 4.2 4.3 Exercise 2
  • 4.3 4.3 Exercise 3
• 5 Chapter 5
  • 5.1 Exercise 5.2
  • 5.2 Exercise 5.3
  • 5.3 Exercise 5.3
• 6 Chapter 9
  • 6.1 Exercise 9.1
  • 6.2 Exercise 9.2
  • 6.3 Exercise 9.3
  • 6.4 Exercise 9.4
• 7 Chapter 10
  • 7.1 Exercise 10.1
  • 7.2 Exercise 10.2
  • 7.3 Exercise 10.3
  • 7.4 Exercise 10.4
  • 7.5 Exercise 10.5
• 8 Chapter 11
  • 8.1 Exercise 11.1
  • 8.2 Exercise 11.2
  • 8.3 Exercise 11.3
  • 8.4 Exercise 11.4
• 9 Chapter 12
  • 9.1 Exercise 12.1
  • 9.2 Exercise 12.2
  • 9.3 Exercise 12.3
• 10 Chapter 13
  • 10.1 Exercise 13.7
• 11 Chapter 14
  • 11.1 Exercise 14.3
  • 11.2 Exercise 14.5
• 12 Chapter 15
  • 12.1 Exercise 15.1
  • 12.2 Exercise 15.3
• 13 Chapter 16
  • 13.1 Exercise 16.1
  • 13.2 Exercise 16.2
  • 13.3 Exercise 16.3
  • 13.4 Exercise 16.4
  • 13.5 Exercise 16.5
  • 13.6 Exercise 16.6
  • 13.7 Exercise 16.7
  • 13.8 Exercise 16.8
• 14 Chapter 17
  • 14.1 Exercise 17.8
• 15 Chapter 3.5
  • 15.1 calculator
  • 15.2 palindrome
  • 15.3 sum of all digits
  • 15.4 Exercise 18.5
• 16 Appendix B
  • 16.1 Exercise B.1
  • 16.2 Exercise B.3

Chapter 1

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Exercise 1.2

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Chapter 2

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Exercise 2.1

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>>> zipcode = 02492 ^SyntaxError: invalid token

>>> zipcode = 02132>>> print zipcode1114

Base 8: 00 01 02 03 04 05 06 07 10 11 12 13 14 15 16 17 20 21 22 23 24Base 10: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20

>>> print 021321114>>> (2*512)+(1*64)+(3*8)+(2*1)1114>>>

Exercise 2.2

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>>> pi = 3.1415926535897932>>> r = 5>>> 4/3*pi*r**3 # This is the wrong answer392.69908169872411>>> r = 5.0 # Radius can be a float here as well, but is not _necessary_.>>> 4.0/3.0*pi*r**3 # Using floats give the correct answer523.5987755982989>>>

 $24.95 Cost $9.98 Discount per book $14.97 Cost per book after discount 60 Total number of books$898.20 Total cost not inc delivery $3.00 First book delivery 59 Remaining books $0.75 Delivery cost for extra books $44.25 Total cost for extra books $47.25 Total Delivery cost$945.45 Total BillThis answer is wrong because 40.0/100.0 return wrong value 0.40000000000000002 for more info see IEEE 754 (Standard for Floating-Point Arithmetic)>>> (24.95-24.95*40.0/100.0)*60+3+0.75*(60-1)945.44999999999993>>> 24.95*0.6*60+0.75*(60-1)+3945.45You can use the decimal module to maintain precision.from decimal import Decimal.....def wholesale_cost(args): d = 1 - args.get('discount')/100 purchase = Decimal(args.get('cost') * d * 60) return purchase + Decimal(args.get('delivery'))args = {'cost': 24.95, 'discount': 40, 'delivery': 3.00+0.75*59}

# Total wholesale book cost calculatorcover_price = 24.95number_of_books = int(input("How many books do you want to order at wholesale? "))def ship_cost (number_of_books): if number_of_books == 1: return (number_of_books * 3) # Cost of shipping one book is $3 else: return (3 + (number_of_books - 1) * 0.75) # Each additional copy of the book is $0.75 to shipdef discounted_price(number_of_books): return(cover_price - (cover_price * .4)) # There is a 40% discount on wholesale book salesdef wholesale_cost(number_of_books): return ((discounted_price(number_of_books) * number_of_books) + ship_cost(number_of_books))print("The cost of buying and shipping", number_of_books, "books is $",round(wholesale_cost(number_of_books), 2))

>>> start = (6*60+52)*60>>> easy = (8*60+15)*2>>> fast = (7*60+12)*3>>> finish_hour = (start + easy + fast)/(60*60.0)>>> finish_floored = (start + easy + fast)//(60*60) #int() function can also be used to get integer value, but it hasn't taught yet.>>> finish_minute = (finish_hour - finish_floored)*60>>> print ('Finish time was %d:%d' % (finish_hour,finish_minute))Finish time was 7:30*** ANOTHER WAY ***start_time_hr = 6 + 52 / 60.0easy_pace_hr = (8 + 15 / 60.0 ) / 60.0tempo_pace_hr = (7 + 12 / 60.0) / 60.0running_time_hr = 2 * easy_pace_hr + 3 * tempo_pace_hrbreakfast_hr = start_time_hr + running_time_hrbreakfast_min = (breakfast_hr-int(breakfast_hr))*60breakfast_sec= (breakfast_min-int(breakfast_min))*60print ('breakfast_hr', int(breakfast_hr) )print ('breakfast_min', int (breakfast_min) )print ('breakfast_sec', int (breakfast_sec) )>>>

Chapter 3

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Exercise 3.1

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>>> def right_justify(s): print (' '*(70-len(s))+s) >>> right_justify('allen') allen>>>

def right_justify(s): total_length = 70 current_length = len(s) current_string = s while current_length < total_length: current_string = " " + current_string current_length = len(current_string) print(current_string)OUTPUT>>> right_justify("monty") monty

Exercise 3.3

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"""Solution to Exercise 3.5 on page 27 of Think PythonAllen B. Downey, Version 1.1.24+Kart [Python 3.2]"""# here is a mostly-straightforward solution to the# two-by-two version of the grid.def do_twice(f): f() f()def do_four(f): do_twice(f) do_twice(f)def print_beam(): print('+ - - - -', end='')def print_post(): print('| ', end='')def print_beams(): do_twice(print_beam) print('+')def print_posts(): do_twice(print_post) print('|')def print_row(): print_beams() do_twice(print_posts)def print_grid(): do_twice(print_row) print_beams()print_grid() ____________ # another solutiondef do_twice(f): f() f()def do_four(f): do_twice(f) do_twice(f)def print_column(): print '+----+----+'def print_row(): print '| | |'def print_rows(): do_four(print_row)def do_block(): print_column() print_rows()def print_block(): do_twice(do_block) print_column()print_block()# nathan moses-gonzales_________# straight-forward solution to 4x4 griddef do_twice(f): f() f()def do_four(f): # not needed for 2x2 grid do_twice(f) do_twice(f)def print_beam(): print('+----', end='')def print_post(): print('| ', end='')def print_beams(): do_twice(print_beam) print('+')def print_posts(): do_twice(print_post) print('|')def print_row(): print_beams() do_twice(print_posts)def print_grid2x2(): do_twice(print_row) print_beams()def print_beam4(): do_four(print_beam) print('+')def print_post4(): do_four(print_post) print('|')def print_row4(): print_beam4() do_twice(print_post4)def print_grid4x4(): do_four(print_row4) print_beam4()print_grid4x4()-----------------------# here is a less-straightforward solution to the# four-by-four grid def one_four_one(f, g, h): f() do_four(g) h()def print_plus(): print '+',def print_dash(): print '-',def print_bar(): print '|',def print_space(): print ' ',def print_end(): printdef nothing(): "do nothing"def print1beam(): one_four_one(nothing, print_dash, print_plus)def print1post(): one_four_one(nothing, print_space, print_bar)def print4beams(): one_four_one(print_plus, print1beam, print_end)def print4posts(): one_four_one(print_bar, print1post, print_end)def print_row(): one_four_one(nothing, print4posts, print4beams)def print_grid(): one_four_one(print4beams, print_row, nothing)print_grid()comment = """After writing a draft of the 4x4 grid, I noticed that many of thefunctions had the same structure: they would do something, dosomething else four times, and then do something else once.So I wrote one_four_one, which takes three functions as arguments; itcalls the first one once, then uses do_four to call the second onefour times, then calls the third.Then I rewrote print1beam, print1post, print4beams, print4posts,print_row and print_grid using one_four_one.Programming is an exploratory process. Writing a draft of a programoften gives you insight into the problem, which might lead you torewrite the code to reflect the structure of the solution.--- Allen"""print comment# another solutiondef beam(): plus = "+" minus = "-"*4 print(plus, minus, plus,minus, plus, minus, plus, minus, plus)def straight(): straight = "|" space = " "*4 print(straight, space, straight, space, straight, space, straight, space, straight, space)def quad_straight(): straight() straight() straight() straight()def twice(): beam() quad_straight() beam() quad_straight()def quad(): twice() twice() beam()quad()-- :)------------------# Without functions. print("+ - - - - " * 2 + "+")print("|\t\t | \t\t|\n" * 3 + "|\t\t | \t\t|")print("+ - - - - " * 2 + "+")print("|\t\t | \t\t|\n " *3 + "|\t\t | \t\t|")print("+ - - - - " * 2 + "+")------------------Why not using the first solution and adapt it to the number of rowsdef do_twice(f): f() f()def do_four(f): do_twice(f) do_twice(f)def print_column(): print '+----+----+----+----+'def print_row(): print '| | | | |'def print_rows(): do_four(print_row)def do_block(): print_column() print_rows()def print_block(): do_twice(do_block) # print_column() do_twice(do_block) print_column()print_block()-----------------------# mteodordef draw_line(bar, middle = ' ', repeat = 2, length = 2): """ Draw a single line like this: [ (B M*repeat)*length B] """ for k in range(length): print("%s %s " % (bar, middle*repeat), end='') print(bar)def draw_grid(length = 2, height = 2, width = 2): """ Draw a grid like this: + -- + -- + | | | | | | + -- + -- + | | | | | | + -- + -- + where: * length x height are the table size * width is the size of a cell/column """ for i in range(height): draw_line('+', '-', width, length) for j in range(length): draw_line('|', ' ', width, length) draw_line('+', '-', width, length)draw_grid(4, 4, 3)--------------------------#kipp# auto adjust size of columnssize=4def beam(): print(" + - - - -"*size, "+")def post(): print(" | "*size, "|")def repeat(func): func() func() func()# manual adjust size for rows# this is 4beam()repeat(post)beam()repeat(post)beam()repeat(post)beam()repeat(post)beam()

Chapter 4

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4.3 Exercise 1

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from TurtleWorld import *world = TurtleWorld()bob = Turtle()def square(t): for i in range(4): fd(t, 100) lt(t)square(bob)wait_for_user()

4.3 Exercise 2

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from TurtleWorld import *world = TurtleWorld()bob = Turtle()print(bob)def square(t, length): t = Turtle() for i in range(4): fd(t, length) lt(t)square(bob, 200)wait_for_user()

4.3 Exercise 3

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from swampy.TurtleWorld import *world = TurtleWorld()bob = Turtle()print(bob)def polygon(t, length, n): for i in range(n): fd(t, length) lt(t, 360 / n)polygon(bob, 50, 8)wait_for_user()

Chapter 5

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Exercise 5.2

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def countdown(a): # A typical countdown function if a < 0: print("Blastoff") elif a > 0: print(a) countdown(a - 1)def call_function(n,a): # The countdown function is called "n" number of times. Any other function can be used instead of countdown function. for i in range(n): countdown(a) call_function(3, 10)

Exercise 5.3

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def is_triangle(a, b, c): if a <= b+c: if b <= a+c: if c <= a+b: return 'yes' else: return 'no' else: return 'no' else: return 'no'is_triangle(1, 12, 1)'no'

Exercise 5.3

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def is_triangle(a, b, c): if a<=b+c and b<=a+c and c<=a+b: return 'yes' else: return 'no'is_triangle(1, 12, 3)'no'

Chapter 9

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Exercise 9.1

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fin = open('words.txt')for line in fin:word = line.strip()if len(word) > 20:print (word)

Exercise 9.2

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fin = open('words.txt')def has_no_e(word): for char in word: if char in 'Ee': return False return True count = 0for line in fin: word = line.strip() if has_no_e(word): count += 1 print (word)percent = (count / 113809.0) * 100print (str(percent)) + "% of the words don't have an 'e'."

Exercise 9.3

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fin = open('words.txt')def avoids(word,letter): for char in word: if char in letter: return False return Trueletter = raw_input('What letters to exclude? ')count = 0for line in fin: word = line.strip() if avoids(word, letter): count += 1 print wordpercent = (count / 113809.0) * 100print str(percent) + "% of the words don't have " + letter + '.'

Exercise 9.4

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def uses_only(word, letters): """returns true if word is made only out of letters else flase""" for letter in word: if letter not in letters: return False return True

Chapter 10

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Exercise 10.1

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def nested_sum(nestedList): ''' nestedList: list composed of nested lists containing int. Returns the sum of all the int in the nested list ''' newList = [] #Helper function to flatten the list def flatlist(nestedList): ''' Returns a flat list ''' for i in range(len(nestedList)): if type(nestedList[i]) == int: newList.append(nestedList[i]) else: flatlist(nestedList[i]) return newList flatlist(nestedList) print sum(newList) nested_sum(nestedList)

Exercise 10.2

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>>> def capitalize_nested(l): def capitalize(s): return s.capitalize() for n, i in enumerate(l): if type(i) is list: l[n] = capitalize_nested(l[n]) elif type(i) is str: l[n] = capitalize(i) return l

Exercise 10.3

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>>> def cumulative(l): cumulative_sum = 0 new_list = [] for i in l: cumulative_sum += i new_list.append(cumulative_sum) return new_list

Exercise 10.4

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>>> def middle(x):res = []i = 1while i <= len(x)-2:res.append(x[i])i += 1return res

>>> def middle(x): return x[1:-1]

Exercise 10.5

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>>> def chop(x):del x[:1]del x[-1:]

Chapter 11

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Exercise 11.1

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fin = open('words.txt')englishdict = dict()def create_diction(): counter = 0 dictionairy = dict() for line in fin: word = line.strip() dictionairy[word] = counter counter += 1 return dictionairy

Exercise 11.2

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def invert_dict(s): i={} for key in s: v=s[key] i.setdefault(v, []).append(key) return i

def histogram(s):d = dict()for c in s:d[c] = d.get(c,0)+1return d

Exercise 11.3

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v = {'p' : 1, 'a' : 1, 'r' : 2, 'o' : 1, 't' : 1}def print_hist(h): d = [] d += sorted(h.keys()) for c in d: print(c, h[c])

v = {'p' : 1, 'a' : 1, 'r' : 2, 'o' : 1, 't' : 1}def print_hist(h): for c in sorted(h.keys()): print c, h[c]

Exercise 11.4

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def reverse_lookup(d,v): l = list() for c in d: if d[c] == v: l.append(c) return l

Chapter 12

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Exercise 12.1

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numbers = (1,2,3)def sumall(numbers): x = 0 for i in numbers: x = x + i print xsumall(numbers)

def sumall(*t): x = 0 for i in range(len(t)): x += t[i] return x

def sumall(*args):t = list(args)return sum(t)

def sumall(*args): return sum(args)

Exercise 12.2

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import randomdef sort_by_length(words):t = []for word in words:t.append((len(word),word))t.sort(reverse=True)res = []for length, word in t:res.append(word)i=0final = []while i <= len(res)-2:if len(res[i]) == len(res[i+1]):y_list = [res[i], res[i+1]]random.shuffle(y_list)final = final + y_listi += 2else:final.append(res[i])i += 1if i == len(res)-1:final.append(res[i])return final

from random import shuffledef sort_by_length(words):r = []d = dict()for word in words:d.setdefault(len(word), []).append(word)for key in sorted(d, reverse=True):if len(d[key]) > 1:shuffle(d[key])r.extend(d[key])return r

Exercise 12.3

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import stringdef most_frequent(s):d = dict()inv = dict()for char in s:if char in string.ascii_letters:letter = char.lower()d[letter] = d.get(letter, 0) + 1for letter, freq in d.items():inv.setdefault(freq, []).append(letter)for freq in sorted(inv, reverse=True):print('{:.2%}:'.format(freq/(sum(list(inv)*len(inv[freq])))), ', '.join(inv[freq]))

Chapter 13

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Exercise 13.7

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from string import punctuation, whitespace, digitsfrom random import randintfrom bisect import bisect_leftdef process_file(filename):h = dict()fp = open(filename)for line in fp:process_line(line, h)return hdef process_line(line, h):line = line.replace('-', ' ')for word in line.split():word = word.strip(punctuation + whitespace + digits)word = word.lower()if word != '':h[word] = h.get(word, 0) + 1hist = process_file('emma.txt')def cum_sum(list_of_numbers):cum_list = []for i, elem in enumerate(list_of_numbers):if i == 0:cum_list.append(elem)else:cum_list.append(cum_list[i-1] + elem)return cum_listdef random_word(h):word_list = list(h.keys())num_list = []for word in word_list:num_list.append(h[word])cum_list = cum_sum(num_list)i = randint(1, cum_list[-1])pos = bisect_left(cum_list, i)return word_list[pos]print(random_word(hist))

Chapter 14

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Exercise 14.3

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import shelvedef dict_of_signatures_and_words(filename='words.txt'):d = dict()for line in open(filename):word = line.lower().strip()signature = ''.join(sorted(word))d.setdefault(signature, []).append(word)return ddef db_of_anagrams(filename='anagrams', d=dict_of_signatures_and_words()):db = shelve.open(filename)for key, values in d.items():if len(values)>1:for index, value in enumerate(values):db[value]=values[:index]+values[index+1:]db.close()def print_contents_of_db(filename='anagrams'):db = shelve.open(filename, flag='r')for key in sorted(db):print(key.rjust(12), '\t<==>\t', ', '.join(db[key]))db.close()db_of_anagrams()print_contents_of_db()

Exercise 14.5

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# Replace urllib.request with urllib if you use Python 2.# I would love to see a more elegant solution for this exercise, possibly by someone who understands html.import urllib.requestdef check(zip_code):if zip_code == 'done':return Falseelse: if len(zip_code) != 5: print('\nThe zip code must have five digits!')return Truedef get_html(zip_code):gibberish = urllib.request.urlopen('http://www.uszip.com/zip/' + zip_code)less_gib = gibberish.read().decode('utf-8')return less_gibdef extract_truth(code, key, delimiter):pos = code.find(key) + len(key)nearly_true = code[pos:pos+40]truth = nearly_true.split(delimiter)[0]return truthwhile True:zip_code = input('Please type a zip code (5 digits) or "done" if want to stop:\n')if not check(zip_code): breakcode = get_html(zip_code)invalid_key = '(0 results)'if invalid_key in code:print('\nNot a valid zip code.')continuename_key = '<title>'name_del = ' zip'name = extract_truth(code, name_key, name_del)pop_key = 'Total population</dt><dd>'pop_del = '<'pop = extract_truth(code, pop_key, pop_del)if not 1 < len(pop) < 9:pop = 'not available'print('\n' + name)print('Population:', pop, '\n')

Chapter 15

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Exercise 15.1

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import mathclass Point(object):"""represents a point in 2-D space"""def distance(p1, p2):distance = math.sqrt((p2.x - p1.x)**2 + (p2.y - p1.y)**2)return distancep1 = Point()p2 = Point()p1.x = 3p1.y = 2p2.x = 4p2.y = 3print(distance(p1, p2))

Exercise 15.3

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import copydef move_rectangle(rec, dx, dy): """ does a deep copy and return the newRec with changes applied """ newRec = copy.deepcopy(rec) newRec.corner.x += dx newRec.corner.y += dy return newRec

Chapter 16

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Exercise 16.1

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def print_time(t): print '%.2d:%.2d:%.2d' % (t.hour, t.minute, t.second)

# Solution for Python3# More on string formatting: http://docs.python.org/py3k/library/string.html#formatspecdef print_time(t): # 0 is a fill character, 2 defines the width print('{}:{:02}:{:02}'.format(t.hour, t.minute, t.second))

Exercise 16.2

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def is_after(t1, t2): return (t1.hour, t1.minute, t1.second) > (t2.hour, t2.minute, t2.second)

Exercise 16.3

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# Comment not by the author: This will give a wrong result, if (time.second + seconds% 60) > 60def increment(time, seconds): n = seconds/60 time.second += seconds - 60.0*n time.minute += n m = time.minute/60 time.minute -= m*60 time.hour += m

# Solution for Python3# Replace '//' by '/' for Python2def increment(time, seconds):time.second += secondstime.minute += time.second//60time.hour += time.minute//60time.second %= 60time.minute %= 60time.hour %= 24

# A different way of going about itdef increment(time, seconds): # Converts total to seconds, then back to a readable format time.second = time.hour*3600 + time.minute*60 + time.second + seconds (time.minute, time.second) = divmod(time_in_seconds, 60) (time.hour, time.minute) = divmod(time.minute, 60)

Exercise 16.4

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# Solution for Python3# Replace '//' by '/' for Python2from copy import deepcopydef increment(time, seconds):r = deepcopy(time)r.second += secondsr.minute += r.second//60r.hour += r.minute//60r.second %= 60r.minute %= 60r.hour %= 24return r

Exercise 16.5

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class Time(object): """represents the time of day. attributes: hour, minute, second"""time = Time()time.hour = 11time.minute = 59time.second = 30def time_to_int(time): minutes = time.hour * 60 + time.minute seconds = minutes * 60 + time.second return secondsdef int_to_time(seconds): time = Time() minutes, time.second = divmod(seconds, 60) time.hour, time.minute = divmod(minutes, 60) return timedef increment(time, addtime): seconds = time_to_int(time) return int_to_time(seconds + addtime)def print_time (x): print 'The time is %.2d: %.2d: %.2d' % (x.hour, x.minute, x.second)print_time (time)newtime = increment (time, 70)print_time (newtime)

Exercise 16.6

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def time_to_int(time):minutes = time.hour * 60 + time.minuteseconds = minutes * 60 + time.secondreturn secondsdef int_to_time(seconds):time = Time()minutes, time.second = divmod(seconds, 60)time.hour, time.minute = divmod(minutes, 60)return timedef mul_time(time, factor):seconds = time_to_int(time)seconds *= factorseconds = int(seconds)return int_to_time(seconds)def average_pace(time, distance):return mul_time(time, 1/distance)

Exercise 16.7

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class Date(object):"""represents a date.attributes: day, month, year"""def print_date(date):# German date formatprint('{}.{}.{}'.format(date.day, date.month, date.year))def is_leap_year(year): # http://en.wikipedia.org/wiki/Leap_year#Algorithmif year % 4 == 0:if year % 100 == 0:if year % 400 == 0:return Truereturn Falsereturn Truereturn Falsedef month_list(year):if is_leap_year(year):return [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]return [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]def days_of_year(year):if is_leap_year(year):return 366return 365def date_to_int(date):days = 0for year in range(1, date.year):days += days_of_year(year)month_days = month_list(date.year)for month in range(1, date.month):days += month_days[month - 1]days += date.day - 1return daysdef int_to_date(days):date = Date()date.year = 1next_days = 365while days >= next_days:date.year += 1days -= next_daysnext_days = days_of_year(date.year)date.month = 1next_days = 31month_days = month_list(date.year)while days >= next_days:date.month += 1days -= next_daysnext_days = month_days[date.month - 1]date.day = days + 1return datedef increment_date(date, n):days = date_to_int(date)return int_to_date(days + n)d1 = Date()d1.day, d1.month, d1.year = 8, 3, 2012print_date(d1)d2 = increment_date(d1, 7)print_date(d2)

Exercise 16.8

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from datetime import datedef current_weekday():i = date.today()print i.strftime('%A')current_weekday()

# Python3 solution. Replace "input" by "raw_input" for Python2.from datetime import datetimedef time_until_birthday(): dob_input = input(('Please enter the date of your birth in ' 'the format "mm/dd/yyyy": ')) dob = datetime.strptime(dob_input, '%m/%d/%Y') now = datetime.now() if now > datetime(now.year, dob.month, dob.day): age = now.year - dob.year next_year = True else: age = now.year - dob.year - 1 next_year = False time_to_birthday = datetime(now.year + next_year, dob.month, dob.day) - now days = time_to_birthday.days hours, remainder = divmod(time_to_birthday.seconds, 3600) minutes, seconds = divmod(remainder, 60) print("\nYou are {} years old.".format(age)) print(("You have {0} days, {1} hours, {2} minutes and {3} " "seconds left until your next birthday.").format( days, hours, minutes, seconds))time_until_birthday()

Chapter 17

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Exercise 17.8

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from visual import scene, spherescene.range = (256, 256, 256)scene.center = (128, 128, 128)t = range(0, 256, 51)for x in t: for y in t: for z in t: pos = x, y, z color = (x/255., y/255., z/255.) sphere(pos=pos, radius=10, color=color)

# As there currently (2013-04-12) is no function read_colors in color_list.py# I use a workaround and simply import the variable COLORS from color_list.py.# I then use the function all_colors() on COLORS to get a list of the colors.from color_list import COLORSfrom visual import scene, spheredef all_colors(colors_string=COLORS): """Extract a list of unique RGB-tuples from COLORS. The tuples look like (r, g, b), where r, g and b are each integers in [0, 255]. """ # split the string into lines and remove irrelevant lines lines = colors_string.split('\n')[2:-2] # split the individual lines and remove the names numbers_only = [line.split()[:3] for line in lines] # turn strings into ints and rgb-lists into tuples rgb_tuples = [tuple([int(s) for s in lst]) for lst in numbers_only] # return a list of unique tuples return list(set(rgb_tuples))def make_spheres(color_tuples=all_colors()): scene.range = (256, 256, 256) scene.center = (128, 128, 128) for (r, g, b) in color_tuples: sphere(pos=(r, g, b), radius=7, color=(r/255., g/255., b/255.))if __name__ == '__main__': make_spheres()

Chapter 3.5

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calculator

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#recursion or recursiveprint "\nINDEX\n""\nC=1 for addition\n""\nC=2 for substraction\n""\nC=3 for multiplication\n""\nC=4 for division\n""\nC=5 for to find modulus\n""\nC=6 to find factorial\n"C=input("Enter your choice here: ")def add(x,y):c=x+yprint x,"+",y,"=",cdef sub(x,y):c=x-yprint x,"-",y,"=",cdef mul(x,y):c=x*yprint x,"*",y,"=",cdef div(x,y):c=x/yprint x,"/",y,"=",cdef mod(x,y):c=x%yprint x,"%",y,"=",cif C==6:def f(n):if n==1:print nreturn nelse:print n,"*",return n*f(n-1)n=input("enter your no here: ")print f(n)if C==1:a=input("Enter your first no here: ")b=input("Enter your second no here: ")add(a,b)elif C==2:a=input("Enter your first no here: ")b=input("Enter your second no here: ")sub(a,b)elif C==3:a=input("Enter your first no here: ")b=input("Enter your second no here: ")mul(a,b)elif C==4:a=input("Enter your first no here: ")b=input("Enter your second no here: ")div(a,b)elif C==5:a=input("Enter your first no here: ")b=input("Enter your second no here: ")mod(a,b)

palindrome

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def first(word):return word[0]def last(word):return word[-1]def middle(word):return word[1:-1]def palindrome(word):if first(word)==last(word):word = middle(word)n=len(word)if n<2:print "palindrome"else:return palindrome(word)else:print "not palindrome"word=raw_input("Enter the string:")palindrome(word)

sum of all digits

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def sum_of_n_numbers(number):if(number==0):return 0else:return number + sum_of_n_numbers(number-1)num = raw_input("Enter a number:")num=int(num)sum = sum_of_n_numbers(num)print sum###another answer in case of while loopsdef sum_of_Digits(number):sum=0while number>0:digit=number%10sum=sum+digitnumber=number/10return sumnum=raw_input("enter the number")num=int(num)sum_of_digits=sum_of_Digits(num)print sum_of_digits

Exercise 18.5

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class Card(object):suit_names = ['Clubs', 'Diamonds', 'Hearts', 'Spades']rank_names = [None, 'Ace', '2', '3', '4', '5', '6', '7', '8', '9', '10', 'Jack', 'Queen', 'King']def __init__(self, suit = 0, rank = 2):self.suit = suitself.rank = rankdef __str__(self):return '%s of %s' % (Card.rank_names[self.rank], Card.suit_names[self.suit])def __cmp__(self, other):c1 = (self.suit, self.rank)c2 = (other.suit, other.rank)return cmp(c1, c2)def is_valid(self):return self.rank > 0class Deck(object):def __init__(self, label = 'Deck'):self.label = labelself.cards = []for i in range(4):for k in range(1, 14):card = Card(i, k)self.cards.append(card)def __str__(self):res = []for card in self.cards:res.append(str(card))print self.labelreturn '\n'.join(res)def deal_card(self):return self.cards.pop(0)def add_card(self, card):self.cards.append(card)def shuffle(self):import randomrandom.shuffle(self.cards)def sort(self):self.cards.sort()def move_cards(self, other, num):for i in range(num):other.add_card(self.deal_card())def deal_hands(self, num_hands, num_cards):if num_hands*num_cards > 52:return 'Not enough cards.'l = []for i in range(1, num_hands + 1):hand_i = Hand('Hand %d' % i)self.move_cards(hand_i, num_cards)l.append(hand_i)return lclass Hand(Deck):def __init__(self, label = ''):self.cards = []self.label = label# 18-6, 1-4:class PokerHand(Hand):def suit_hist(self):self.suits = {}for card in self.cards:self.suits[card.suit] = self.suits.get(card.suit, 0) + 1return self.suitsdef rank_hist(self):self.ranks = {}for card in self.cards:self.ranks[card.rank] = self.ranks.get(card.rank, 0) + 1return self.ranksdef P(self):self.rank_hist()for val in self.ranks.values():if val >= 2:return Truereturn Falsedef TP(self):self.rank_hist()count = 0for val in self.ranks.values():if val == 4:return Trueelif val >= 2 and val < 4:count += 1return count >= 2def TOAK(self):self.rank_hist()for val in self.ranks.values():if val >= 3:return Truereturn Falsedef STRseq(self):seq = []l = STRlist()self.rank_hist()h = self.ranks.keys()h.sort()if len(h) < 5:return []# Accounts for high Aces:if 1 in h:h.append(1)for i in range(5, len(h)+1):if h[i-5:i] in l:seq.append(h[i-5:i])return seqdef STR(self):seq = self.STRseq()return seq != []def FL(self):self.suit_hist()for val in self.suits.values():if val >= 5:return Truereturn Falsedef FH(self):d = self.rank_hist()keys = d.keys()for key in keys:if d[key] >= 3:keys.remove(key)for key in keys:if d[key] >= 2:return Truereturn Falsedef FOAK(self):self.rank_hist()for val in self.ranks.values():if val >= 4:return Truereturn Falsedef SFL(self):seq = self.STRseq()if seq == []:return Falsefor list in seq:list_suits = []for index in list:for card in self.cards:if card.rank == index:list_suits.append(card.suit)list_hist = histogram(list_suits)for key in list_hist.keys():if list_hist[key] >= 5:return Truereturn Falsedef classify(self):self.scores = []hands = ['Pair', 'Two-Pair','Three of a Kind', 'Straight','Flush', 'Full House','Four of a Kind', 'Straight Flush']if self.P():self.scores.append(1)if self.TP():self.scores.append(2)if self.TOAK():self.scores.append(3)if self.STR():self.scores.append(4)if self.FL():self.scores.append(5)if self.FH():self.scores.append(6)if self.FOAK():self.scores.append(7)if self.SFL():self.scores.append(8)if self.scores != []:return hands[max(self.scores)-1]def STRlist():s = []for i in range(0,9):s.append(range(1,14)[i:i+5])s.append([10,11,12,13,1])return sdef histogram(l):d = dict()for k in range(len(l)):d[l[k]] = 1 + d.get(l[k],0)return d# 18-6, 5:def p(config = '', trials = 10000, n = 1):"""Estimates probability that thenth dealt hand will be config. A handconsists of seven cards."""successes = 0for i in range(1, trials + 1):deck = Deck('Deck %d' % i)deck.shuffle()box = Hand()deck.move_cards(box, (n-1)*7)hand = PokerHand('Poker Hand %d' % i)deck.move_cards(hand, 7)if hand.classify() == config:successes += 1return 1.0*successes/trials#Iterate until first desired config.:if __name__ == '__main__':c = 1while True:deck = Deck()deck.shuffle()hand = PokerHand('Poker Hand %d' % c)deck.move_cards(hand, 5)print handprint hand.SFL()if hand.SFL():print hand.STRseq()breakprint ''c += 1Code by Victor Alvarez

Appendix B

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Exercise B.1

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Exercise B.3

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from bisect import bisect_leftdef bisection(sorted_list, item): i = bisect_left(sorted_list, item) if i < len(sorted_list) and sorted_list[i] == item: return i else: return Noneif __name__ == '__main__': a = [1, 2, 3] print(bisection(a, 2)) # expect 1 b = [1, 3] print(bisection(b, 2)) # expect None c = [1, 2] print(bisection(c, 3)) # expect None