You may work with one partner on this assignment. If you work with a partner, put your name and the name of your partner in the list of authors at the top of your program. Only one partner needs to run handin21 to submit the files for the group. Both partners will receive the same grade.

Run update21, if you haven't already, to create the cs21/labs/08 directory. Then cd into your cs21/labs/08 directory and create the python programs for lab 8 in this directory (handin21 looks for your lab 8 assignments in your cs21/labs/08 directory):

$ update21
$ cd cs21/labs/08
$ vi lingo.py

For this assignment, you will write a program that implements the TV game show Lingo. The focus of this assignment is for you to practice using top-down design to construct your solution incrementally.

Lingo is a turn-based guessing game. The computer selects a random word and the player tries to guess the word. Each guess must also be a valid word of the same length (this is what makes the game interesting and hard). After a guess is made, the computer provides status information about how close (or how far) the player is to arriving at the solution. The status information includes which letters are correct, but in the wrong position, and which letters are correct, and in the right position.

To make things concrete, let's use an example where the computer is selecting a five-letter word. Normally, as a player of the game, you would not know what the computer had chosen. However, let's make things easier and peek at the computer's choice: guava.

It's time for you to begin guessing the word. Your initial guess is: spray. Notice that there is only one letter that you guessed that's also in the target word (the letter a). Rather than indicate the number of letters you have correct, the status message will specify which letters are exactly correct and which are in the sequence, but in the wrong place. You'll do this by UPPER-CASING the exact matches, leaving the 'inexact' matches alone, and replacing the wrong letters with dashes. So, in this case, where the letter a of your guess spray is an 'inexact' match, you'd receive the status message:
---a-

Clearly you don't know the word yet, so you make another guess: arrow. Again, the only correct letter is the a, and now it's in a different wrong place. So, the status you would receive is:
a----

Your next guess is again. This time the guessed word has two a's, as does the secret word. The first guessed a is in the wrong position and will appear as lower case, but the second guessed a is in the correct position (the third character) and should show up as an upper case guess in the status. There is also a correctly guessed g but it is in the wrong position and will appear as lower case. Since neither the i nor the n appear in the target word, the status of this guess is the following: agA--

Your next guess is games. While it's true that you know there are no s's in the solution (from your guess of spray earlier), you're trying to see if some of these other letters are present (the m and e) and you're still trying to figure out where the other a goes. The status message now that you have the g in the right position and the a is still in the wrong position:
Ga---

Here is this example as it may appear in a game (see the Sample Output section below for other examples of a working solution):

Enter a 5 letter word: spray
- - - a -
Enter a 5 letter word: arrow
a - - - -
Enter a 5 letter word: again
a g A - -
Enter a 5 letter word: games
G a - - -
Enter a 5 letter word: curve
- U - V -
Enter a 5 letter word: suave
- U A V -
Enter a 5 letter word: guava
You won in 7 turns!

• The length of the words to be used for this game is 5.
• The secret words will be drawn from the online dictionary stored in: /usr/share/dict/words. You should read into a list, all the words from this dictionary that are the appropriate length (5) and that consist of only lower-case alphabetic characters (i.e. they are not proper nouns nor do they have special characers like hyphens in them).
• The player may not guess arbitrary sequences of letters; the player's guesses must be valid English words of the specified length. If the player enters a non-word or a word that is not the correct length, print out an error message and prompt them to enter a valid word.
• The status information must show inexact matches (correct letter but in incorrect position in the word) in lower case letters and exact matches (correct letter in correct postion in the word) in upper case letters.
• Allow the user to give up and see the secret word by entering the word QUIT all in upper case letters.
• You should use Top-Down Design and your program's structure should reflect this.

• In python, you can test whether a particular word, called word is in a list of words, called wordList by doing:

  if word in wordList:
     ...
  

• In python, you can convert a string, such as word = "apple" into a list ['a', 'p', 'p', 'l', 'e'], simply by doing: list(word). You can then join the list of characters back into a word as shown in the interaction below:

  >>> word = "apple"
  >>> word 
  'apple'
  >>> charList = list(word)
  >>> charList
  ['a', 'p', 'p', 'l', 'e']
  >>> rejoined = ''.join(charList)
  >>> rejoined
  'apple'
  

• Producing the appropriate status information is the trickiest aspect of implementing this program. You will need to re-compute the status after each guess from the user.

  You may want to first get the entire flow of control correct, with incorrect status updates (perhaps ignoring double characters in guessed and target word, and ignoring the correct position part) , and then go back and work on getting the status update part correct.

  We suggest that you store the secret word and the guessed word as strings. Then to produce the status information, create list versions of these words that can be modified. You can use the list version of the guessed word to hold the status information. First search for exact matches. When an exact match is found, change the letter in the guessed word to upper case and hide the letter in the secret word by changing it to some other character, such as '.' (you don't want to find it again when you search for inexact matches).

  For example, given the target word guava and the user guess gulag, we expect the status message: GU-a-. We'll start by converting both the target and the guess into lists:

  target: ['g','u','a','v','a']     guess: ['g','u','l','a','g']

  Now, we'll check for exact matches, beginning from left to right in the guess list. "Does the first letter of 'gulag' match the first letter of 'guava'?" It does, so we'll capitalize the first letter of the guess list and we'll change the first letter of the target list to a period:

  target: ['.','u','a','v','a']     guess: ['G','u','l','a','g']

  Next, "Does the second letter of 'gulag' match the second letter of 'guava'?" It does again, so we'll capitalize the second letter of the guess list and we'll change the second letter of the target list to a period:

  target: ['.','.','a','v','a']     guess: ['G','U','l','a','g']

  Next, we'll ask if the third, fourth, or fifth letters match, and none will, so the two lists will remain unchanged.

  We move on to finding inexact matches. For each letter in the guess list, we do the following:

  1. if the letter is capitalized (it was an exact match), we ignore it.
  2. if the letter is in the target list, we replace the target letter with '.'
  3. otherwise, we replace the guess letter with a '-'.

  Following this algorithm, we look at the first letter is the guess list: G. Since it's capitalized, we go on to the next letter: U. It, too, is capitalized, so we move on to the third letter, l, which is not in the target list, so we replace the letter in the guess list with a '-':

  target: ['.','.','a','v','a']     guess: ['G','U','-','a','g']

  The fourth letter in the guess list, a, is in the target list, so we replace the letter in the target list with a '.':

  target: ['.','.','.','v','a']     guess: ['G','U','-','a','g']

  The final letter in the guess list, g, is not in the target list, so replace the letter in the guess list with a '-':

  target: ['.','.','.','v','a']     guess: ['G','U','-','a','-']

  The guess list is now nearly the status information which you need to provide. You just need to join the letters in the list together to form the string 'GU-a-'.

Here is some sample output from three runs of a lingo program, notice the error handling:

$ python lingo.py

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
 Welcome to Lingo
   Each turn you will try to guess the secret word
   If you guess the word, you win
   If you guess some letters in the word, lingo will display:
     guessed letters in the correct position in upper case
     guessed letters in the incorrect position in lower case
 Good Luck!
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

word:  -  -  -  -  - 
Guess a  5 letter word: hello

word:  -  e  l  -  - 
Guess a  5 letter word: letter
Invalid Input, enter a word with 5 characters. try again...
Guess a  5 letter word: oops
Invalid Input, enter a word with 5 characters. try again...
Guess a  5 letter word: helpm
Invalid Input, helpm is not a valid word. try again...
Guess a  5 letter word: piles

word:  P  I  l  E  - 
Guess a  5 letter word: pixel

You guessed the word in 3 tries.  Congratulations!


$ python lingo.py

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
 Welcome to Lingo
   Each turn you will try to guess the secret word
   If you guess the word, you win
   If you guess some letters in the word, lingo will display:
     guessed letters in the correct position in upper case
     guessed letters in the incorrect position in lower case
 Good Luck!
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

word:  -  -  -  -  - 
Guess a  5 letter word: snort

word:  -  -  -  r  - 
Guess a  5 letter word: retort
Invalid Input, enter a word with 5 characters. try again...
Guess a  5 letter word: great

word:  -  r  -  a  - 
Guess a  5 letter word: barks

word:  b  A  r  -  - 
Guess a  5 letter word: rstuv
Invalid Input, rstuv is not a valid word. try again...
Guess a  5 letter word: roles

word:  R  -  -  -  - 
Guess a  5 letter word: ramps

word:  R  A  -  -  - 
Guess a  5 letter word: rabid

word:  R  A  B  i  - 
Guess a  5 letter word: rabbi

You guessed the word rabbi in 7 tries.  Congratulations!


$ python lingo.py

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
 Welcome to Lingo
   Each turn you will try to guess the secret word
   If you guess the word, you win
   If you guess some letters in the word, lingo will display:
     guessed letters in the correct position in upper case
     guessed letters in the incorrect position in lower case
 Good Luck!
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

word:  -  -  -  -  - 
Guess a  5 letter word: grill

word:  -  -  i  l  - 
Guess a  5 letter word: trips

word:  t  -  i  p  - 
Guess a  5 letter word: QUIT

The word you were trying to guess is: plait
Better luck next time!

Do not attempt any of these until you have the required part done and fully tested. Some extra features to add if you have time:

1. Have the user enter the size of the word s/he wants to use for the game. Your program should correctly test for invalid input (size cannot be negative or zero, nor an alpabetic charater(s)), and it should read in all words of the user's chosen size from the dictionary file.

2. Add a graphics component to your game. You could think of highlighting guessed letters in a certain color or a certain colored containing box. Take a look at the first picture on this page (the one with rows of guessed words) to get some ideas. If you try this one, you should submit two separate programs for lab 8 (one which is your solution to the basic lab 8 assignment, the other which is your solution with a graphical user interface). Copy your working basic solution to a new file, lingo_withgraphics.py, and add graphics to this new file so that you still have a separate file, lingo.py, that contains your solution without graphics.

Warning: When you get this working, be prepared to spend a while playing as it is remarkably addictive!

Once you are satisfied with your program, hand it in by typing handin21 in a terminal window.