12.7. Exercises

1. Write a program that allows the user to enter a string. It then prints a table of the letters of the alphabet in alphabetical order which occur in the string together with the number of times each letter occurs. Case should be ignored. A sample run of the program might look this this:

   Please enter a sentence: ThiS is String with Upper and lower case Letters.
   a  2
   c  1
   d  1
   e  5
   g  1
   h  2
   i  4
   l  2
   n  2
   o  1
   p  2
   r  4
   s  5
   t  5
   u  1
   w  2
   $
   

   x = input("Enter a sentence") x = x.lower() # convert to all lowercase alphabet = 'abcdefghijklmnopqrstuvwxyz' letter_count = {} # empty dictionary for char in x: if char in alphabet: # ignore any punctuation, numbers, etc if char in letter_count: letter_count[char] = letter_count[char] + 1 else: letter_count[char] = 1 keys = letter_count.keys() for char in sorted(keys): print(char, letter_count[char])

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2. Give the Python interpreter’s response to each of the following from a continuous interpreter session:

   1. >>> d = {'apples': 15, 'bananas': 35, 'grapes': 12}
      >>> d['banana']
      

   2. >>> d['oranges'] = 20
      >>> len(d)
      

   3. >>> 'grapes' in d
      

   4. >>> d['pears']
      

   5. >>> d.get('pears', 0)
      

   6. >>> fruits = d.keys()
      >>> fruits.sort()
      >>> print(fruits)
      

   7. >>> del d['apples']
      >>> 'apples' in d
      

   Be sure you understand why you get each result. Then apply what you have learned to fill in the body of the function below, and add code for the tests indicated:

   def add_fruit(inventory, fruit, quantity=0): pass # make these tests work... new_inventory = {} add_fruit(new_inventory, 'strawberries', 10) # test that 'strawberries' in new_inventory # test that new_inventory['strawberries'] is 10 add_fruit(new_inventory, 'strawberries', 25) # test that new_inventory['strawberries'] is now 35)

3. Write a program called alice_words.py that creates a text file named alice_words.txt containing an alphabetical listing of all the words, and the number of times each occurs, in the text version of Alice’s Adventures in Wonderland. (You can obtain a free plain text version of the book, along with many others, from http://www.gutenberg.org.) The first 10 lines of your output file should look something like this

   Word	Count
   a	631
   a-piece	1
   abide	1
   able	1
   about	94
   above	3
   absence	1
   absurd	2

   How many times does the word, alice, occur in the book? If you are writing this in the activecode window simply print out the results rather than write them to a file.

   f = open('alice.txt', 'r')
   
   count = {}
   
   for line in f:
       for word in line.split():
   
           # remove punctuation
           word = word.replace('_', '').replace('"', '').replace(',', '').replace('.', '')
           word = word.replace('-', '').replace('?', '').replace('!', '').replace("'", "")
           word = word.replace('(', '').replace(')', '').replace(':', '').replace('[', '')
           word = word.replace(']', '').replace(';', '')
   
           # ignore case
           word = word.lower()
   
           # ignore numbers
           if word.isalpha():
               if word in count:
                   count[word] = count[word] + 1
               else:
                   count[word] = 1
   
   keys = count.keys()
   keys.sort()
   
   # save the word count analysis to a file
   out = open('alice_words.txt', 'w')
   
   for word in keys:
       out.write(word + " " + str(count[word]))
       out.write('\n')
   
   print("The word 'alice' appears " + str(count['alice']) + " times in the book.")
   

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4. What is the longest word in Alice in Wonderland? How many characters does it have?

5. Here’s a table of English to Pirate translations

   English	Pirate
   sir	matey
   hotel	fleabag inn
   student	swabbie
   boy	matey
   madam	proud beauty
   professor	foul blaggart
   restaurant	galley
   your	yer
   excuse	arr
   students	swabbies
   are	be
   lawyer	foul blaggart
   the	th’
   restroom	head
   my	me
   hello	avast
   is	be
   man	matey

   Write a function named translator that takes a parameter containing a sentence in English (no punctuation and all words in lowercase) and returns that sentence translated to Pirate.

   For example, the sentence “hello there students” should be translated to “avast there swabbies”.

   def translator(english): pirate = {} pirate['sir'] = 'matey' pirate['hotel'] = 'fleabag inn' pirate['student'] = 'swabbie' pirate['boy'] = 'matey' pirate['restaurant'] = 'galley' pirate['hello'] = 'avast' pirate['students'] = 'swabbies' # Complete the function ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(translator("hello there students"),'avast there swabbies','translator("hello there students") yields "avast there swabbies"') self.assertEqual(translator("the boy stayed in the hotel"),'the matey stayed in the fleabag inn','translator("the boy stayed in the hotel") yields "the matey stayed in the fleabag inn"') myTests().main()

   def translator(sentence): pirate = {} pirate['sir'] = 'matey' pirate['hotel'] = 'fleabag inn' pirate['student'] = 'swabbie' pirate['boy'] = 'matey' pirate['restaurant'] = 'galley' pirate['hello'] = 'avast' pirate['students'] = 'swabbies' psentence = [] words = sentence.split() for aword in words: if aword in pirate: psentence.append(pirate[aword]) else: psentence.append(aword) return " ".join(psentence)

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