根据值对python中的元组进行排序 [英] Sorting tuples in python based on their values

问题描述

我正在尝试使用以下代码来打印前10个常见单词.但是，它不起作用.关于如何解决它的任何想法?

I am trying to print the top 10 frequent words using the following code. However, its not working. Any idea on how to fix it?

def reducer_count_words(self, word, counts):
    # send all (num_occurrences, word) pairs to the same reducer.
    # num_occurrences is so we can easily use Python's max() function.
    yield None, (sum(counts), word)




# discard the key; it is just None
def reducer_find_max_10_words(self, _, word_count_pairs):
    # each item of word_count_pairs is (count, word),
    # so yielding one results in key=counts, value=word

        tmp = sorted(word_count_pairs)[0:10]
        yield tmp

推荐答案

tmp = sorted(word_count_pairs, key=lambda pair: pair[0], reverse=True)[0:10]

说明:

• sorted()的key参数允许您在比较之前在每个元素上运行一个函数.
• lambda pair: pair[0]是一个从word_count_pairs中提取数字的函数.
• reverse以降序而不是升序排序.

• The key parameter of sorted() allows you to run a function on each element before comparison.
• lambda pair: pair[0] is a function that extracts the number from your word_count_pairs.
• reverse sorts in descending order, instead of ascending order.

来源:

• https://wiki.python.org/moin/HowTo/Sorting#Key_Functions
• https://docs.python.org/2/library/functions. html#sorted

• https://wiki.python.org/moin/HowTo/Sorting#Key_Functions
• https://docs.python.org/2/library/functions.html#sorted

放在一边:如果您有很多不同的单词，则对整个列表进行排序以找到前十名是无效的.有更有效的算法.另一个答案中提到的most_common()方法可能利用了更有效的算法.

aside: If you have many different words, sorting the entire list to find the top ten is inefficient. There are much more efficient algorithms. The most_common() method mentioned in another answers probably utilizes a more efficient algorithm.

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