功能导入不正确

Question

我是自学自学 Python通过麻省理工学院的OCW获得6.00。 （所以，请不要评论“你不应该问作业问题”......我甚至不在麻省理工学院，就像我喜欢的那样）。我目前被卡在Problem #3 in Problem Set #5 。

这里是ps5.py的（相关）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 

我跑的代码，并返回正确的结果。

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} 

我的问题是，当is_valid_word函数被导入到test_ps5.py，它似乎只返回False的一切，这意味着它失败的测试案例的一半。

这里是test_ps5.py的（相关）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() 

而这里的结果，当我运行代码：

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! 

我不明白什么是造成问题的位置和原因。

Answer 1

问题不在于您发布的代码中。这工作得很好：

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() 

在同一目录下两个文件，这里的输出：

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

你暗示数倍你会留下很多“不相关”的代码。除了从文件中加载单词列表外，这个问题似乎没有任何代码需要。该问题必须位于您未显示的代码中。由于这个问题似乎并不需要，所以我建议或者（a）全部摆脱; （b）一步一步地去除它，直到你的问题得到解决，然后逐步增加回来并定期测试，这样你就可以准确地看到代码的哪一点会导致它崩溃;或者（c）只需在当前代码中的战略位置插入大量print语句，以便您可以确切地看到它失败的位置和原因，这将为您提供有关正在发生的事情的线索，并帮助您确定哪些代码造成的问题。

你也不会告诉你如何叫test_is_valid_word()，所以它可能是一个简单的问题。

from something import *通常也是一个坏主意，有时会导致命名空间污染导致的神秘问题。改为尝试from ps5 import update_hand, is_valid_word，看看是否有帮助。

没有代码的其余部分（这又一次看起来不相关），你是唯一能够做这些事情的人。