Question

ps3a Problem 3 help needed. How do I compare dictionaries if there is no order?

here is the link to the problem set: http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-00sc-introduction-to-computer-science-and-programming-spring-2011/unit-1/lecture-7-debugging/MIT6_00SCS11_ps3.pdf

I see that there are two parts to this question-

1. Must test if word is in word_list
2. If the letters in word are in hand

I solve the first by the first if/else pair but am stuck with the second part. Here are some approaches I have tried:

Approach 1:

ref=('hello', 'bye', 'butts', 'helllo')
hand={'h':2, 'e':1, 'l':2, 'o':1}


def is_valid_word(word, hand, word_list):
"""
Returns True if word is in the word_list and is entirely
composed of letters in the hand. Otherwise, returns False.
Does not mutate hand or word_list.

word: string
hand: dictionary (string -> int)
word_list: list of lowercase strings
"""
# TO DO...
if word in word_list:
for letter in word:
hand[letter]-=1
#print hand
if hand[letter]>=0:
return True
else:
return False
else:
return False

#print is_valid_word('hello', hand, ref)
print is_valid_word('helllo', hand, ref)
#print is_valid_word('bye', hand, ref)

In this approach I attempt to mutate the dictionary hand so that for each letter in word the value associated with the key (letter in word) is reduced by 1. Then, I attempt to test if the new value in hand is >= 0 (the idea being if it is >=0 then there are enough letters in the hand).

Approach 2:

I wont post the code, but essentially I was attempting to turn the word played into a dictionary using the provided function. At this point, I was unsure how to proceed as I don't know how to compare dicts since they are not ordered like lists. I thought about converting both hand and the dict derived from word to lists then comparing but couldn't figure out how.

Thanks for the help!

Answer 1

If you want to compare dictionaries, iterate through the keys in one, and as long as the second one.has_key( <key> ), they're matching.

Answer 2

?