python - 获取句子中字母的频率

Question

我正在尝试编写一个代码，可以在其中输入随机句子，并计算字母在此字符串中返回的次数:

def getfreq(lines):
    """ calculate a list with letter frequencies

    lines - list of lines (character strings)

    both lower and upper case characters are counted.
    """
    totals = 26*[0]
    chars = []
    for line in lines:
       for ch in line:
           chars.append(totals)

    return totals

    # convert totals to frequency
    freqlst = []
    grandtotal = sum(totals)

    for total in totals:
        freq = totals.count(chars)
        freqlst.append(freq)
    return freqlst

到目前为止，我已经实现了将输入的每个字母附加到列表(字符)中。但现在我需要一种方法来计算字符在该列表中返回的次数，并以频率表示。

Answer 1

没有collections.Counter:

import collections

sentence = "A long sentence may contain repeated letters"

count = collections.defaultdict(int)  # save some time with a dictionary factory
for letter in sentence:  # iterate over each character in the sentence
    count[letter] += 1  # increase count for each of the sentences

或者，如果您确实想完全手动完成:

sentence = "A long sentence may contain repeated letters"

count = {}  # a counting dictionary
for letter in sentence:  # iterate over each character in the sentence
    count[letter] = count.get(letter, 0) + 1  # get the current value and increase by 1

在这两种情况下，count 字典都会将每个不同的字母作为其键，其值将是遇到字母的次数，例如:

print(count["e"])  # 8

如果您想让它不区分大小写，请务必在将其添加到计数时调用 letter.lower()。