2nd/10_Wiki/Topics/Topic_Programming/Topic_Python/Python_Recursion.md

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

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-recursion	Python Recursion	Programming_Language	draft	conceptual		recursive function base case 파이썬 재귀		B	0.9	2026-07-04	2026-07-04			python programming w3schools recursion	https://www.w3schools.com/python/python_recursion.asp

Python Recursion

🎯 한 줄 통찰 (One-line insight)

Every recursive function needs a base case that stops the recursion — without one, it calls itself forever and hits Python's default ~1000-call recursion limit, raising a stack-related error. [S1]

🧠 핵심 개념 (Core concepts)

• Recursion — a function calling itself; useful for looping through data to reach a result. [S1]
• Base case — the condition that stops the recursion. [S1]
• Recursive case — the function calling itself with a modified (usually smaller) argument. [S1]
• Risk — without a base case, infinite recursion causes a stack overflow / excess memory/CPU use. [S1]
• sys.getrecursionlimit() / sys.setrecursionlimit() — inspect/raise the default recursion depth limit (~1000), with a caution against raising it carelessly. [S1]

🧩 추출된 패턴 (Extracted patterns)

• List recursion via slicing — processing a list recursively (sum_list, find_max) typically uses numbers[1:] to shrink the list each call, with an empty-list or single-element check as the base case. [S1]
• Prefer iteration for very deep recursion — the source explicitly recommends switching to iteration rather than raising the recursion limit for cases needing very deep recursion. [S1]

📖 세부 내용 (Details)

• Simple countdown: def countdown(n): if n <= 0: print("Done!") else: print(n); countdown(n - 1). [S1]
• Factorial with explicit base/recursive case: def factorial(n): if n == 0 or n == 1: return 1; else: return n * factorial(n - 1). [S1]
• Fibonacci via recursion: def fibonacci(n): if n <= 1: return n; else: return fibonacci(n-1) + fibonacci(n-2). [S1]
• List sum via recursion: def sum_list(numbers): if len(numbers) == 0: return 0; else: return numbers[0] + sum_list(numbers[1:]). [S1]
• Recursion limit: import sys; print(sys.getrecursionlimit()). [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 트리/그래프 탐색처럼 자연스럽게 재귀적인 구조를 다룰 때 표준적으로 쓰인다. [S1]

💻 코드 패턴 (Code patterns)

Base case and recursive case (Python):

def factorial(n):
    if n == 0 or n == 1:      # base case
        return 1
    else:                      # recursive case
        return n * factorial(n - 1)

✅ 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 Functions, Python Generators, Python Lists
• 참조 맥락: 자기 자신을 호출하는 함수 패턴 — 반드시 base case가 있어야 안전하다.

📚 출처 (Sources)

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

📝 변경 이력 (Change history)

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