如何使用正则表达式仅移除字符串中与字母拼接或位于单词字符间的数字（保留日期及独立数字）

Great question! Your current regex re.sub(r'[0-9]+', '', newString) is too broad—it yanks out every digit it finds, regardless of context. Let's tweak it to only remove digits that are directly attached to letters (either before, after, or sandwiched between them), while preserving:

• Date ordinal numbers like 21st, 3rd, or 10th
• Standalone numbers (e.g., 26 in "26 alphabets" or 5 as a standalone value)

The Revised Regex #

Here's the pattern you need:

import re

newString = re.sub(r'(?<=[a-zA-Z])\d+|\d+(?=[a-zA-Z])(?!(?:st|nd|rd|th)\b)', '', newString)

Breakdown of the Pattern #

Let's break down each part to understand how it works:

• (?<=[a-zA-Z])\d+: Matches digits that come right after a letter (e.g., the 123 in abc123 or a1b). The (?<=...) is a positive lookbehind—only match digits if a letter precedes them.
• |: Acts as an "or" operator to combine two matching rules.
• \d+(?=[a-zA-Z])(?!(?:st|nd|rd|th)\b):
  • \d+(?=[a-zA-Z]) matches digits that come right before a letter (e.g., the 123 in 123abc). The (?=...) is a positive lookahead—only match digits if a letter follows them.
  • (?!(?:st|nd|rd|th)\b) is a negative lookahead that excludes date ordinals. It says: "Don't match these digits if they're immediately followed by st, nd, rd, or th (ending at a word boundary)." This preserves values like 21st or 3rd.

Test Cases to Verify #

Let's put this regex to the test with your examples and more scenarios:

Edge Case Adjustment (If Needed) #

If you also need to handle underscores (since \w includes underscores), replace [a-zA-Z] with [a-zA-Z_] in the pattern. But based on your question, focusing on letters should be sufficient.

内容的提问来源于stack exchange，提问作者Namra Rehman