Python

Question

正如标题所说，我需要编写一个代码，其中 return 是一个包含频率最高的 5 个单词（来自输入字符串）的列表。这是我目前所拥有的：

from collections import defaultdict

def top5_words(text):
  tally = defaultdict(int)
  words = text.split()

  for word in words:
    if word in tally:
      tally[word] += 1
    else:
      tally[word] = 1

  answer = sorted(tally, key=tally.get, reverse = True)

  return(answer)

例如，如果您输入：top5_words("one one was a racehorse two two was one too")，它应该 return：["one"、"two"、"was"、 "a", "racehorse"] 而是 returns: ['one', 'was', 'two', 'racehorse', 'too', 'a'] - 有人知道这是为什么吗？

编辑：

感谢 Anand S Kumar，这就是我现在得到的：

import collections

def top5_words(text):

  counts =  collections.Counter(text.split())

  return [elem for elem, _ in sorted(counts.most_common(),key=lambda x:(-x[1], x[0]))[:5]]

Answer 1

你应该使用 collections.Counter and then you can use its method - most_common() 。示例 -

import collections
def top5_words(text):
    counts = collections.Counter(text.split())
    return counts.most_common(5)

请注意，上面 returns 是一个包含 5 个元组的列表，在每个元组中，第一个元素是实际单词，第二个元素是该单词的计数。

演示 -

>>> import collections
>>> def top5_words(text):
...     counts = collections.Counter(text.split())
...     return counts.most_common(5)
...
>>> top5_words("""As the title says, I need to write a code that returns a list of 5 words (from an input string) that have the highest frequency. This is what I have so far""")
[('that', 2), ('a', 2), ('I', 2), ('the', 2), ('have', 2)]

如果您只需要元素而不是计数，那么您还可以使用列表理解来获取该信息。示例 -

import collections
def top5_words(text):
    counts = collections.Counter(text.split())
    return [elem for elem, _ in counts.most_common(5)]

演示 -

>>> import collections
>>> def top5_words(text):
...     counts = collections.Counter(text.split())
...     return [elem for elem, _ in counts.most_common(5)]
...
>>> top5_words("""As the title says, I need to write a code that returns a list of 5 words (from an input string) that have the highest frequency. This is what I have so far""")
['that', 'a', 'I', 'the', 'have']

对于评论中的新要求 -

it seems there's still an issue when it comes to words with the same frequency, how would I get it to sort same frequency words alphabetically?

您可以先获取所有单词及其计数的列表，然后使用 sorted 这样 sorted 首先对计数进行排序，然后对元素本身进行排序（因此当计数为相同的）。示例 -

import collections
def top5_words(text):
    counts = collections.Counter(text.lower().split())
    return [elem for elem, _ in sorted(counts.most_common(),key=lambda x:(-x[1], x[0]))[:5]]

演示 -

>>> import collections
>>> def top5_words(text):
...     counts = collections.Counter(text.lower().split())
...     return [elem for elem, _ in sorted(counts.most_common(),key=lambda x:(-x[1], x[0]))[:5]]
...
>>> top5_words("""As the title says, I need to write a code that returns a list of 5 words (from an input string) that have the highest frequency. This is what I have so far""")
['a', 'have', 'i', 'that', 'the']

Python - Return 出现频率最高的前 5 个词

Python - Return top 5 words with highest frequency

sorting

dictionary

frequency