计算文本文件中所有字母的出现次数[重复]答案

【问题标题】：Counting the occurrences of all letters in a txtfile [duplicate]计算文本文件中所有字母的出现次数[重复]
【发布时间】：2017-01-08 04:20:37
【问题描述】：

我正在尝试打开一个文件并计算字母的出现次数。

到目前为止，这是我所在的位置：

def frequencies(filename):
    infile=open(filename, 'r')
    wordcount={}
    content = infile.read()
    infile.close()
    counter = {}
    invalid = "‘'`,.?!:;-_\n—' '"

    for word in content:
        word = content.lower()
        for letter in word:
            if letter not in invalid:
                if letter not in counter:
                    counter[letter] = content.count(letter)
                    print('{:8} appears {} times.'.format(letter, counter[letter]))

任何帮助将不胜感激。

【问题讨论】：

标签： python-3.x dictionary text-files counting

【解决方案1】：

最好的方法是使用 numpy 包，例子是这样的

import numpy
text = "xvasdavawdazczxfawaczxcaweac"
text = list(text)
a,b = numpy.unique(text, return_counts=True)
x = sorted(zip(b,a), reverse=True)
print(x)

在您的情况下，您可以将所有单词组合成单个字符串，然后将字符串转换为字符列表如果要删除除字符之外的所有内容，可以使用正则表达式来清理它

#clean all except character
content = re.sub(r'[^a-zA-Z]', r'', content)
#convert to list of char
content = list(content)
a,b = numpy.unique(content, return_counts=True)
x = sorted(zip(b,a), reverse=True)
print(x)

【讨论】：

【解决方案2】：

如果您正在寻找不使用numpy 的解决方案：

invalid = set([ch for ch in  "‘'`,.?!:;-_\n—' '"])

def frequencies(filename):
    counter = {}
    with open(filename, 'r') as f:
        for ch in (char.lower() for char in f.read()):
            if ch not in invalid:
                if ch not in counter:
                    counter[ch] = 0
                counter[ch] += 1

        results = [(counter[ch], ch) for ch in counter]
        return sorted(results)

for result in reversed(frequencies(filename)):
    print result

【讨论】：

【解决方案3】：

我建议改用collections.Counter。

紧凑型解决方案

from collections import Counter
from string import ascii_lowercase # a-z string

VALID = set(ascii_lowercase)

with open('in.txt', 'r') as fin:
    counter = Counter(char.lower() for line in fin for char in line if char.lower() in VALID)
    print(counter.most_common()) # print values in order of most common to least.

更具可读性的解决方案。

from collections import Counter
from string import ascii_lowercase # a-z string

VALID = set(ascii_lowercase)

with open('in.txt', 'r') as fin:
    counter = Counter()
    for char in (char.lower() for line in fin for char in line):
        if char in VALID:
            counter[char] += 1
    print(counter)

如果您不想使用Counter，那么您可以使用dict。

from string import ascii_lowercase # a-z string

VALID = set(ascii_lowercase)

with open('test.txt', 'r') as fin:
    counter = {}
    for char in (char.lower() for line in fin for char in line):
        if char in VALID:
            # add the letter to dict
            # dict.get used to either get the current count value
            # or default to 0. Saves checking if it is in the dict already
            counter[char] = counter.get(char, 0) + 1
    # sort the values by occurrence in descending order
    data = sorted(counter.items(), key = lambda t: t[1], reverse = True)
    print(data)

【讨论】：