"""
字典setdefault方法的使用:
d.setdefault(k, [default]):
如果有k，则返回。如果没有则让 k = default，然会返回default

案例： 统计文本中每个单词出现的位置
格式: {'单词‘，[(行号， 列号)，(行号，列号)]}
"""

import re
import sys

# 返回Pattern对象
WORD_RE = re.compile(r'\w+')  # [A-Za-z0-9_]

index = {}
with open('./zen.txt', encoding='utf-8') as fp:
    for line_no, line in enumerate(fp, 1):  # 获得行号和一行数据
        for match in WORD_RE.finditer(line):  # 匹配每一行中的每个单词
            word = match.group()
            column_no = match.start() + 1   # start() 该单词在整个串中的位置
            location = (line_no, column_no)

            # occurrences = index.get(word, [])  # <1>
            # occurrences.append(location)       # <2>
            # index[word] = occurrences          # <3>
            
            index.setdefault(word, []).append(location)


print(index)

for word in sorted(index, key=str.upper):  # <4>
    print(word, index[word])

zen.txt:

The Zen of Python, by Tim Peters

Beautiful is better than ugly.
Explicit is better than implicit.

输出：

{'The': [(1, 1)], 'Zen': [(1, 5)], 'of': [(1, 9)], 'Python': [(1, 12)], 'by': [(1, 20)], 'Tim': [(1, 23)], 'Peters': [(1, 27)], 'Beautiful': [(3, 1)], 'is': [(3, 11), (4, 10)], 'better': [(3, 14), (4, 13)], 'than': [(3, 21), (4, 20)], 'ugly': [(3, 26)], 'Explicit': [(4, 1)], 'implicit': [(4, 25)]}
Beautiful [(3, 1)]
better [(3, 14), (4, 13)]
by [(1, 20)]
Explicit [(4, 1)]
implicit [(4, 25)]
is [(3, 11), (4, 10)]
of [(1, 9)]
Peters [(1, 27)]
Python [(1, 12)]
than [(3, 21), (4, 20)]
The [(1, 1)]
Tim [(1, 23)]
ugly [(3, 26)]
Zen [(1, 5)]

Process finished with exit code 0