功能導入不正確

Question

我是自學自學 Python通過麻省理工學院的OCW獲得6.00。 （所以，請不要評論「你不應該問作業問題」......我甚至不在麻省理工學院，就像我喜歡的那樣）。我目前被卡在Problem #3 in Problem Set #5 。

這裏是ps5.py的（相關）部分：

def update_hand(hand, word): 
    """ 
    Uses up all the letters in the given word and returns 
    the new hand. Does not modify hand. 

    word: string 
    hand: dictionary (string -> int) 
    """ 
    hand = hand.copy() 
    for char in word: 
     hand[char] = hand.get(char,0)-1 
    return hand 

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 
    """ 
    if word not in word_list: 
     return False 
    after = update_hand(hand.copy(),word) 
    for char in after: 
     if after[char] < 0: 
      return False 
    return True 

我跑的代碼，並返回正確的結果。

Loading word list from file... 
    83667 words loaded. 
play_game not implemented. 
play_hand not implemented. 
>>> word = "python" 
>>> hand = {'h':1,'n':1,'o':1,'p':1,'t':1,'y':1} 
>>> word_list = load_words() 
Loading word list from file... 
    83667 words loaded. 
>>> is_valid_word(word, hand, word_list) 
True 
>>> word = "cobra" 
>>> is_valid_word(word, hand, word_list) 
False 
>>> hand 
{'h': 1,'n': 1,'o': 1,'p': 1,'t': 1,'y': 1} 

我的問題是，當is_valid_word函數被導入到test_ps5.py，它似乎只返回False的一切，這意味着它失敗的測試案例的一半。

這裏是test_ps5.py的（相關）部分：

from ps5 import * 

def test_is_valid_word(word_list): 
    """ 
    Unit test for is_valid_word 
    """ 
    failure=False 
    # test 1 
    word = "hello" 
    hand = {'h':1, 'e':1, 'l':2, 'o':1} 
    if not is_valid_word(word, hand, word_list): 
     print "FAILURE: test_is_valid_word()" 
     print "\tExpected True, but got False for word: '" + word + "' and hand:", hand 
     failure = True 
    # test 2 passes 
    # test 3 
    hand = {'n': 1, 'h': 1, 'o': 1, 'y': 1, 'd':1, 'w':1, 'e': 2} 
    word = "honey" 
    if not is_valid_word(word, hand, word_list): 
     print "FAILURE: test_is_valid_word()" 
     print "\tExpected True, but got False for word: '"+ word +"' and hand:", hand 
     failure = True 
    # test 4 passes 
    # test 5 
    hand = {'e':1, 'v':2, 'n':1, 'i':1, 'l':2} 
    word = "evil" 
    if not is_valid_word(word, hand, word_list): 
     print "FAILURE: test_is_valid_word()" 
     print "\tExpected True, but got False for word: '" + word + "' and hand:", hand 
     failure = True 
    # test 6 passes 
    if not failure: 
     print "SUCCESS: test_is_valid_word()" 

word_list = load_words() 

而這裏的結果，當我運行代碼：

Loading word list from file... 
    83667 words loaded. 
---------------------------------------------------------------------- 
Testing get_word_score... 
SUCCESS: test_get_word_score() 
---------------------------------------------------------------------- 
Testing update_hand... 
SUCCESS: test_update_hand() 
---------------------------------------------------------------------- 
Testing is_valid_word... 
FAILURE: test_is_valid_word() 
    Expected True, but got False for word: 'hello' and hand: {'h': 1, 'e': 1, 'l': 2, 'o': 1} 
FAILURE: test_is_valid_word() 
    Expected True, but got False for word: 'honey' and hand: {'e': 2, 'd': 1, 'h': 1, 'o': 1, 'n': 1, 'w': 1, 'y': 1} 
FAILURE: test_is_valid_word() 
    Expected True, but got False for word: 'evil' and hand: {'i': 1, 'n': 1, 'e': 1, 'l': 2, 'v': 2} 
---------------------------------------------------------------------- 
All done! 

我不明白什麼是造成問題的位置和原因。

Answer 1

問題不在於您發佈的代碼中。這工作得很好：

ps5.py：

def update_hand(hand, word): 
    """ 
    Uses up all the letters in the given word and returns 
    the new hand. Does not modify hand. 

    word: string 
    hand: dictionary (string -> int) 
    """ 
    hand = hand.copy() 
    for char in word: 
     hand[char] = hand.get(char,0)-1 
    return hand 

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 
    """ 
    if word not in word_list: 
     return False 
    after = update_hand(hand.copy(),word) 
    for char in after: 
     if after[char] < 0: 
      return False 
    return True 

words.py：

#!/usr/bin/env python 

from ps5 import * 

def test_is_valid_word(word_list): 
    """ 
    Unit test for is_valid_word 
    """ 
    failure=False 
    # test 1 
    word = "hello" 
    hand = {'h':1, 'e':1, 'l':2, 'o':1} 
    if not is_valid_word(word, hand, word_list): 
     print "FAILURE: test_is_valid_word()" 
     print "\tExpected True, but got False for word: '" + word + "' and hand:", hand 
     failure = True 
    # test 2 passes 
    # test 3 
    hand = {'n': 1, 'h': 1, 'o': 1, 'y': 1, 'd':1, 'w':1, 'e': 2} 
    word = "honey" 
    if not is_valid_word(word, hand, word_list): 
     print "FAILURE: test_is_valid_word()" 
     print "\tExpected True, but got False for word: '"+ word +"' and hand:", hand 
     failure = True 
    # test 4 passes 
    # test 5 
    hand = {'e':1, 'v':2, 'n':1, 'i':1, 'l':2} 
    word = "evil" 
    if not is_valid_word(word, hand, word_list): 
     print "FAILURE: test_is_valid_word()" 
     print "\tExpected True, but got False for word: '" + word + "' and hand:", hand 
     failure = True 
    # test 6 passes 
    if not failure: 
     print "SUCCESS: test_is_valid_word()" 


def main(): 
    wordlist = ['honey', 'evil', 'python', 'dogs', 'weasels', 'hello'] 
    test_is_valid_word(wordlist) 

if __name__ == '__main__': 
    main() 

在同一目錄下兩個文件，這裏的輸出：

paul@local:~/Documents/src/sandbox$ ./words.py 
SUCCESS: test_is_valid_word() 
paul@local:~/Documents/src/sandbox$ 

你暗示數倍你會留下很多「不相關」的代碼。除了從文件中加載單詞列表外，這個問題似乎沒有任何代碼需要。該問題必須位於您未顯示的代碼中。由於這個問題似乎並不需要，所以我建議或者（a）全部擺脫; （b）一步一步地去除它，直到你的問題得到解決，然後逐步增加回來並定期測試，這樣你就可以準確地看到代碼的哪一點會導致它崩潰;或者（c）只需在當前代碼中的戰略位置插入大量print語句，以便您可以確切地看到它失敗的位置和原因，這將爲您提供有關正在發生的事情的線索，並幫助您確定哪些代碼造成的問題。

你也不會告訴你如何叫test_is_valid_word()，所以它可能是一個簡單的問題。

from something import *通常也是一個壞主意，有時會導致命名空間污染導致的神祕問題。改爲嘗試from ps5 import update_hand, is_valid_word，看看是否有幫助。

沒有代碼的其餘部分（這又一次看起來不相關），你是唯一能夠做這些事情的人。