有输入时如何计数

Question

我试图编写一个函数，它不接受输入，而是要求一个名称。如果您输入一个空字符串，函数应该为每个名字打印同名的人数。

例如：

>>>name()
Enter a name: Paul
Enter a name: Bill
Enter a name: John
Enter a name: Paul
Enter a name: Nick
Enter a name: Bill
Enter a name: Bill
Enter a name:    
There is 1 person named John
There is 1 person named Nick
There are 2 people named Paul
There are 3 people named Bill

到目前为止，我已经：

def name():
    name = input ('Enter a name: ')
    count = 0

    while name:
        if name == input ('Enter a name: '):
            count = count + 1
        else:
            print (count)

我敢肯定我没有数对。您将如何正确执行此功能，以及在不知道将有多少不同名称的情况下如何区分不同的输入并对其进行计数？

此外，如果可能的话，我想在我还在学习的时候学习基本代码，即使它不高效。

Answer 1

from collections import defaultdict
dic = defaultdict(int)
while True:
    name = input ('Enter a name: ')
    if name:
        dic[name] += 1
    else:
        for k,v in sorted(dic.items(), key = lambda x: (x[1],x[0])):
            print ("There is {} person named {}".format(v,k))
        break    

演示：

$ python3 so.py
Enter a name: Paul
Enter a name: Bill
Enter a name: John
Enter a name: Paul
Enter a name: Nick
Enter a name: Bill
Enter a name: Bill
Enter a name: 
There is 1 person named John
There is 1 person named Nick
There is 2 person named Paul
There is 3 person named Bill

Answer 2

Python附带了一个专门用于计数的集合，称为计数器。

import collections

counts = collections.Counter()

while True:
    name = input('Enter a name: ')
    if not name:
        break
    counts[name] += 1

for name, count in counts.items():
    print('There is {} person named {}'.format(count, name))

如果您希望结果从最不常见到最常见的顺序，计数器有一个按计数排序的函数，most_common。不幸的是，它是向后的...但是你可以通过调用反向来解决这个问题：

for name, count in reversed(counts.most_common()):
    print('There is {} person named {}'.format(count, name))

或者，如果您喜欢按名称排序：

for name, count in sorted(counts.items()):
    print('There is {} person named {}'.format(count, name))

Answer 3

只是为了好玩，一句话这样做：

>>> collections.Counter(iter(functools.partial(input, "Enter a name: "), ""))
Enter a name: Paul
Enter a name: Bill
Enter a name: John
Enter a name: Paul
Enter a name: Nick
Enter a name: Bill
Enter a name: Bill
Enter a name: 
Counter({'Bill': 3, 'Paul': 2, 'Nick': 1, 'John': 1})

这可能不是在真实代码中实现的方法。