Question

Having some trouble with PS3, part 3 testing valid words. Not sure where my code is going wrong but I cant shake the test failure.

Answer 1

My code:

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
"""
hand2 = get_frequency_dict(word)

if word in word_list:
for x in hand2:
if hand2[x] <=hand[x]:
return 'True'
else:
return 'False'

Answer 2

The failures:

FAILURE: test_is_valid_word()
Expected True, but got False for word: 'hello' and hand: {'l': 2, 'h': 1, 'e': 1, 'o': 1}
FAILURE: test_is_valid_word()
Expected True, but got False for word: 'honey' and hand: {'d': 1, 'h': 1, 'o': 1, 'y': 1, 'n': 1, 'e': 2, 'w': 1}
FAILURE: test_is_valid_word()
Expected True, but got False for word: 'evil' and hand: {'l': 2, 'i': 1, 'n': 1, 'e': 1, 'v': 2}

Answer 3

I don't know python, but I'll post some logic of how I'd solve it
```
function isValidWord(word, hand, word_list) {

var iterator = 0;

//first, make sure word contains only characters in hand
while iterator < word.length {
if( character at position iterator, in string word is not contained in hand ) {
return false;
//can check if the character is in hand or not by looping over all the characters
//in hand, and if there is never a match, then return false
}
iterator = iterator+1;
}

//second make sure word is a word contained in word_list
iterator = 0;
looping over all elements of word_list {
if(word == word_list[ position iterator ]) {
//then at this point we know it passes the hand test, and wordlist test
return true;
}

iterator = iterator+1;
}

//at this point in code, it passed hand test, but no matches were found in
//the wordlist
return false;

}
```

It's always helpful to print out information throughout the program to help debug too. I know someone who reads python would be a much bigger help, but hopefully this helps somewhat.

Answer 4

I'm not an expert in Python, but I think your problem is that you're making the unsupported assumption that hand[x] and hand2[x] represent the same letter.

Answer 5

Welp, I think the problem is that your function returns the strings 'True' or 'False', when it should return the booleans True or False ;) The test tells you it got False, but I'm guessing it would have said that if your function had returned anything that wasn't the boolean True.

Answer 6

@kizolk, Python isn't a strongly types language. false and "False" evaluate the same.

@shh, After studying the problem a bit more, my answer isn't right either. Does the program have tests that do pass? Can you output the dictionary generated by get_frequency_dict(word) so you can manually compare them and make sure you're getting the expected results?

Answer 7

I changed from string to boolean and did some print statements to see if the values match, which they did. There is no mutation going on in the hands.
Also something I noticed: I looked at the solutions posted for the class, and even when I implement their defined code, I get a similar failure, except it was returning all true instead of all false like mine is.

The only thing I can think of is something to do with using python 3 ( what I use ) and them using python 2.5.x.

I know print and input are different between the two, but not sure what else. Will try to rewrite it for python 2.5.x when I get home and post the results.

Answer 8

I'd look very closely at the code where the inputs/parameters don't provide the output you expect, use a lot of print statements during the input/output in question, and make sure that each line of code is acting as you intend it to.

Answer 9

Okay, found the solution to the problem. Turns out it is an error in going from 2.x to 3.x, the solution can be seen in this post: http://forums.xkcd.com/viewtopic.php?f=20&t=72920#p2973046

Answer 10

Thanks for all your help and ideas in solving this bug!