如何将字典值转换为 csv 文件？

Question

我绝对是 Python 的初学者。我正在对希腊戏剧进行文本分析并计算每个词的词频。由于剧本很长，我无法看到我的全部数据，它只显示出现频率最低的单词，因为Pythonwindow中没有足够的space。我正在考虑将其转换为 .csv 文件。我的完整代码如下：

#read the file as one string and spit the string into a list of separate words
input = open('Aeschylus.txt', 'r')
text = input.read()
wordlist = text.split()

#read file containing stopwords and split the string into a list of separate words
stopwords = open("stopwords .txt", 'r').read().split()

#remove stopwords
wordsFiltered = []

for w in wordlist:
    if w not in stopwords:
        wordsFiltered.append(w)

#create dictionary by counting no of occurences of each word in list
wordfreq = [wordsFiltered.count(x) for x in wordsFiltered]

#create word-frequency pairs and create a dictionary 
dictionary = dict(zip(wordsFiltered,wordfreq))

#sort by decreasing frequency and print
aux = [(dictionary[word], word) for word in dictionary]
aux.sort()
aux.reverse()
for y in aux: print y

import csv


with open('Aeschylus.csv', 'w') as csvfile:
    fieldnames = ['dictionary[word]', 'word']
    writer = csv.DictWriter(csvfile, fieldnames=fieldnames)


    writer.writeheader()
    writer.writerow({'dictionary[word]': '1', 'word': 'inherited'})
    writer.writerow({'dictionary[word]': '1', 'word': 'inheritance'})
    writer.writerow({'dictionary[word]': '1', 'word': 'inherit'})

我在互联网上找到了 csv 的代码。我希望得到的是从最高频率到最低频率的完整数据列表。使用我现在拥有的这段代码，python 似乎完全忽略了 csv 部分，只是打印数据，就好像我没有为 csv 编码一样。

知道我应该编写什么代码才能看到我的预期结果吗？

谢谢。

Answer 1

因为你有一本字典，其中单词是键，它们的频率是值，所以 DictWriter 不适合。它适用于共享一些公共键集的映射序列，用作 csv 的列。例如，如果您有一个您手动创建的字典列表：

a_list = [{'dictionary[word]': '1', 'word': 'inherited'},
          {'dictionary[word]': '1', 'word': 'inheritance'},
          {'dictionary[word]': '1', 'word': 'inherit'}]

那么 DictWriter 将是完成这项工作的工具。但是你有一个 dictionary 像：

dictionary = {'inherited': 1,
              'inheritance': 1,
              'inherit': 1,
              ...: ...}

但是，您已经构建了 (freq, word) 对的排序列表 aux，这非常适合写入 csv:

with open('Aeschylus.csv', 'wb') as csvfile:
    header = ['frequency', 'word']
    writer = csv.writer(csvfile)
    writer.writerow(header)
    # Note the plural method name
    writer.writerows(aux)

python seems to be totally ignoring the csv part and just printing the data as if I didn't code for the csv.

听起来很奇怪。至少你应该得到一个文件 Aeschylus.csv 包含：

dictionary[word],word
1,inherited
1,inheritance
1,inherit

您的频率统计方法还可以改进。目前

#create dictionary by counting no of occurences of each word in list
wordfreq = [wordsFiltered.count(x) for x in wordsFiltered]

必须为 wordsFiltered 中的每个单词遍历列表 wordsFiltered，因此 O(n²)。您可以改为遍历文件中的单词、过滤和计数。 Python 有一个专门用于计算可散列对象的字典，称为 Counter:

from __future__ import print_function
from collections import Counter
import csv

# Many ways to go about this, could for example yield from (<gen expr>)
def words(filelike):
    for line in filelike:
        for word in line.split():
            yield word

def remove(iterable, stopwords):
    stopwords = set(stopwords)  # O(1) lookups instead of O(n)
    for word in iterable:
        if word not in stopwords:
            yield word

if __name__ == '__main__':
    with open("stopwords.txt") as f:
        stopwords = f.read().split()

    with open('Aeschylus.txt') as wordfile:
        wordfreq = Counter(remove(words(wordfile), stopwords))

然后，和以前一样，打印单词及其频率，从最常见的开始：

    for word, freq in wordfreq.most_common():
        print(word, freq)

And/or 写成 csv:

    # Since you're using python 2, 'wb' and no newline=''
    with open('Aeschylus.csv', 'wb') as csvfile:
        writer = csv.writer(csvfile)
        writer.writerow(['word', 'freq'])
        # If you want to keep most common order in CSV as well. Otherwise
        # wordfreq.items() would do as well.
        writer.writerows(wordfreq.most_common())

如何将字典值转换为 csv 文件？

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