Question

我尝试定义一个函数，以以频率递减的顺序打印单词的字母，使用字典和元组。两个类似的问题是Counting repeated characters in a string in Python和How to write a function that takes a string and prints the letters in decreasing order of frequency?，但区别在于排序（按频率）部分和算法。

这是我写的： -

def most_frequent(string):
    d = dict()        #Created a dictionary
    for c in string:
        d[c] = d.get(c,0)+1  #Employed the get method to get the value of the key c
    t = d.items()     #Created a list of tuples of key-value pairs
    for letter, frequency in t:
        letter, frequency = frequency, letter  #Swapped the elements of the tuples
    t.sort(reverse = True)     #Sorting in descending order
    for frequency, letter in t:
        print (frequency," ",letter)

当我用“bookshopkeeper”作为参数调用函数时产生的错误消息是： -

    Traceback (most recent call last):
      File "<pyshell#2>", line 1, in <module>
        most_frequent("bookshopkeeper")
      File "<pyshell#1>", line 8, in most_frequent
        t.sort(reverse = True)
    AttributeError: 'dict_items' object has no attribute 'sort'

我使用get方法来消除if条件的使用。我正在使用python 3.3。请修复代码。非常感谢。

Answer 1

您最好使用collections.Counter。

dct = collections.Counter(string)
print(dct.most_common())
print(list(reversed(dct.most_common())))  # least common :-)

使用字典和元组编写函数根据频率打印字符串的字母

1 个答案: