import collections

import re

WORD_RE = re.compile(r'\w+')

index = collections.defaultdict(list) #用list方法作为默认工厂创建一个默认字典

with open('xx.txt',encoding='utf-8') as fp:

    for line_no,line in enumerate(fp,1):

        for match in WORD_RE.findeiter(line):

            word = match.group()

            column_no = match.start()+1

            location = (line_no,column_no)

            index[word].append(location) # 如果index没有Word记录，会调用默认工厂，创建一个空列表

for word in sorted(index,key=str.upper):

    print(word,index[word])

import collections

class StrKeyDict(collections.UserDict):

    def __missing__(self,key):

        if isinstance(key,str):

            raise KeyError(key)

        return self[str(key)]

    def __contains__(self,key):

        return str(key) in self.data

    def __setitem__(self,key,item):

        self.data[str(key)] = item

import collections

from types import MappingProxyType

d = {1:'A'}

d_proxy = MappingProxyType(d)

d_proxy[1] # A

d_proxy[2] #报错因为不可变

d_proxy[2] = 'B' #{1:'A',2:'B'}