Question

我阅读了与该部分相关的所有答案，但仍然不了解1部分。以下代码到底是做什么的？

random.sample(WORDS, snippet.count("%%%"))

我知道这意味着＆＃34; ###＆＃34;的出现次数。在片段中，但没有得到它究竟意味着什么。

如果有帮助，这是整个代码：

import random
from urllib import urlopen
import sys

WORD_URL = "http://learncodethehardway.org/words.txt"
WORDS = []

PHRASES = {
    "class %%%(%%%):":
      "Make a class named %%% that is-a %%%.",
    "class %%%(object):\n\tdef __init__(self, ***)" :
      "class %%% has-a __init__ that takes self and *** parameters.",
    "class %%%(object):\n\tdef ***(self, @@@)":
      "class %%% has-a function named *** that takes self and @@@ parameters.",
    "*** = %%%()":
      "Set *** to an instance of class %%%.",
    "***.***(@@@)":
      "From *** get the *** function, and call it with parameters self, @@@.",
    "***.*** = '***'":
      "From *** get the *** attribute and set it to '***'."
}

# do they want to drill phrases first
if len(sys.argv) == 2 and sys.argv[1] == "english":
    PHRASE_FIRST = True
else:
    PHRASE_FIRST = False

# load up the words from the website
for word in urlopen(WORD_URL).readlines():
    WORDS.append(word.strip())


def convert(snippet, phrase):
    class_names = [w.capitalize() for w in
                   random.sample(WORDS, snippet.count("%%%"))]
    other_names = random.sample(WORDS, snippet.count("***"))
    results = []
    param_names = []

    for i in range(0, snippet.count("@@@")):
        param_count = random.randint(1,3)
        param_names.append(', '.join(random.sample(WORDS, param_count)))

    for sentence in snippet, phrase:
        result = sentence[:]

        # fake class names
        for word in class_names:
            result = result.replace("%%%", word, 1)

        # fake other names
        for word in other_names:
            result = result.replace("***", word, 1)

        # fake parameter lists
        for word in param_names:
            result = result.replace("@@@", word, 1)

        results.append(result)

    return results


# keep going until they hit CTRL-D
try:
    while True:
        snippets = PHRASES.keys()
        random.shuffle(snippets)

        for snippet in snippets:
            phrase = PHRASES[snippet]
            question, answer = convert(snippet, phrase)
            if PHRASE_FIRST:
                question, answer = answer, question

            print question

            raw_input("> ")
            print "ANSWER:  %s\n\n" % answer
except EOFError:
    print "\nBye"

Answer 1

代码从WORDS获取random elements。由于字符串中可能包含多个%%%占位符，因此%%%中snippet的出现次数与该列表中的项目数相同。

Answer 2

snippets包含字典PHRASES（snippets = PHRASES.keys()）的键。

["***.*** = '***'", '*** = %%%()', 'class %%%(object):\n\tdef ***(self, @@@)', '***.***(@@@)', 'class %%%(object):\n\tdef __init__(self, ***)', 'class %%%(%%%):']

对于每个“snippet”，convert函数将使用snippet（例如"***.*** = '***'"或'class %%%(%%%):'）和{{1}来调用}，phrase字典中的snippet的相应值（分别为PHRASES和"From *** get the *** attribute and set it to '***'."）。

'Make a class named %%% that is-a %%%.'部分returns random.sample(WORDS, snippet.count("%%%"))中与WORDS %%%的{{1}}一样多的单词列表。

>>> snippet.count("%%%")
2
>>> random.sample(WORDS, snippet.count("%%%"))
['cook', 'crush']
...
>>> snippet.count("%%%")
0
>>> random.sample(WORDS, snippet.count("%%%"))
[]

Python - 学习Python困难之路练习41迷茫吗？

2 个答案: