正则表达式：在数字后跟字母时添加空格

Question

在一组数字之后，我想在字符串中添加一个空格。例如，以下字符串应在数字后添加一个空格：

Before                           After
"0ABCD TECHNOLOGIES SERVICES"    "0 ABCD TECHNOLOGIES SERVICES"
"ABCD0 TECHNOLOGIES SERVICES"    "ABCD 0 TECHNOLOGIES SERVICES"

"ABCD 0TECHNOLOGIES SERVICES"    "ABCD 0 TECHNOLOGIES SERVICES"
"ABCD TECHNOLOGIES0 SERVICES"    "ABCD TECHNOLOGIES 0 SERVICES"

"ABCD TECHNOLOGIES 0SERVICES"    "ABCD TECHNOLOGIES 0 SERVICES"
"ABCD TECHNOLOGIES SERVICES0"    "ABCD TECHNOLOGIES SERVICES 0"

我一直在尝试通过以下方式在 Python 中处理正则表达式：

text= re.sub(r'([0-9]+)?([A-Za-z]+)?([0-9]+)?',
             r'\1 \2 \3',
             text,
             0,
             re.IGNORECASE)

使用前面的代码，我得到了影响其他正则表达式转换的不需要的空格：

"0 abcd     technologies     services   "

如何在字符串中添加空格而不添加不需要的空格？

Answer 1

你可以使用

re.sub(r'(?<=\d)(?=[^\d\s])|(?<=[^\d\s])(?=\d)', ' ', text)

请参阅regex demo。

模式详情

• (?<=\d)(?=[^\d\s]) - 数字和字符之间的位置，而不是数字和空格
• | - 或
• (?<=[^\d\s])(?=\d) - 字符而非数字与空格和数字之间的位置。

Python test:

import re
tests = ['0ABCD TECHNOLOGIES SERVICES',
'ABCD0 TECHNOLOGIES SERVICES',
'ABCD 0TECHNOLOGIES SERVICES',
'ABCD TECHNOLOGIES0 SERVICES',
'ABCD TECHNOLOGIES 0SERVICES',
'ABCD TECHNOLOGIES SERVICES0']

rx = re.compile(r'(?<=\d)(?=[^\d\s])|(?<=[^\d\s])(?=\d)')

for test in tests:
    print(rx.sub(' ', test))

输出：

0 ABCD TECHNOLOGIES SERVICES
ABCD 0 TECHNOLOGIES SERVICES
ABCD 0 TECHNOLOGIES SERVICES
ABCD TECHNOLOGIES 0 SERVICES
ABCD TECHNOLOGIES 0 SERVICES
ABCD TECHNOLOGIES SERVICES 0