2nd/10_Wiki/Topics/Domain_Programming/Topic_Python/Python_RegEx.md

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id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
python-regex	Python RegEx	Programming_Language	draft	conceptual		re module regular expressions 파이썬 정규식		B	0.9	2026-07-04	2026-07-04			python programming w3schools regex re	https://www.w3schools.com/python/python_regex.asp

Python RegEx

🎯 한 줄 통찰 (One-line insight)

The re module's four core functions each answer a different question — findall() (all matches as a list), search() (first Match object or None), split() (list split at matches), sub() (replace matches) — and a Match object itself carries .span(), .string, .group() for inspecting what actually matched. [S1]

🧠 핵심 개념 (Core concepts)

• re module — Python's built-in package for regular expressions. [S1]
• re.findall(pattern, txt) — returns a list of ALL matches (empty list if none). [S1]
• re.search(pattern, txt) — returns a Match object for the FIRST match, or None if no match. [S1]
• re.split(pattern, txt, maxsplit) — splits the string at each match; maxsplit limits the split count. [S1]
• re.sub(pattern, repl, txt, count) — replaces matches; count limits replacements. [S1]
• Metacharacters — [] set, \ special sequence/escape, . any char, ^ starts-with, $ ends-with, */+/? occurrence counts, {} exact count, | or, () group. [S1]
• Special sequences — \d digit, \D non-digit, \s whitespace, \S non-whitespace, \w word char, \W non-word char, \b/\B word boundary, \A/\Z string start/end. [S1]
• Flags — re.IGNORECASE, re.MULTILINE, re.DOTALL, etc. [S1]
• Match object properties — .span() (start/end tuple), .string (original input string), .group() (the matched substring). [S1]

📖 세부 내용 (Details)

• Basic search: x = re.search("^The.*Spain$", txt). [S1]
• All matches: x = re.findall("ai", txt). [S1]
• First match only: x = re.search("\s", txt); x.start(). [S1]
• Split at matches: x = re.split("\s", txt). [S1]
• Replace matches: x = re.sub("\s", "9", txt). [S1]
• Match object inspection: x = re.search(r"\bS\w+", txt); print(x.span()); print(x.group()). [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 텍스트 검증/추출(이메일 형식 검사 등)에서 표준적으로 쓰이는 도구다. [S1]

💻 코드 패턴 (Code patterns)

Match object inspection (Python):

import re
txt = "The rain in Spain"
x = re.search(r"\bS\w+", txt)
print(x.span())   # (12, 18)
print(x.group())  # Spain

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.90
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: Python Tutorial
• 관련 개념: Python Strings Methods, Python Modules
• 참조 맥락: 패턴 기반 문자열 검색/치환의 표준 도구 — 문자열 메서드로 처리하기 어려운 패턴 매칭에 사용.

📚 출처 (Sources)

• [S1] W3Schools — Python RegEx — https://www.w3schools.com/python/python_regex.asp

📝 변경 이력 (Change history)

• 2026-07-04: Initial draft synthesized from the W3Schools "Python RegEx" page (Astra wiki-curation, P-Reinforce v3.1 format).