2nd/10_Wiki/Topic_Programming/From_Other/Iteration.md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-iteration	Iteration	10_Wiki/Topics	verified	self	Iterative Development Loop Iterate	none	A	0.9	applied	methodology agile python control-flow generators		2026-05-10	pending	language framework python general

Iteration

매 한 줄

"매 small step, 매 feedback, 매 adjust, 매 repeat". Iteration 매 dual concept — (1) programming control flow (for, while, generators) 와 (2) development methodology (small increments + feedback loop). 2026 LLM-assisted 시대 매 iteration 매 even tighter — 매 minute 매 cycle 가능.

매 핵심

매 Programming iteration

• Eager: for x in list — 매 list 매 fully materialized.
• Lazy: generator, iterator — 매 on-demand pull.
• Async: async for x in stream — 매 I/O 의 overlap.
• Parallel: joblib, multiprocessing.Pool.imap — 매 CPU-bound iteration.

매 Methodology iteration

• Loop: hypothesis → build → measure → learn.
• Cadence: daily (LLM-assisted), weekly (sprint), monthly (release).
• Artifact per cycle: shippable increment.
• Feedback source: tests, users, metrics, code review.

매 응용

1. Data pipeline (process N rows lazily).
2. ML hyperparameter search (iteratively narrow).
3. Agile sprint (2-week cycle).
4. LLM agentic loop (think → act → observe → repeat).

💻 패턴

Pattern 1: Generator (lazy iteration)

def read_jsonl(path: str):
    """매 1GB+ file 의 stream — 매 memory O(1)."""
    import json
    with open(path) as f:
        for line in f:
            yield json.loads(line)

for record in read_jsonl("events.jsonl"):
    process(record)

Pattern 2: Itertools combinators

from itertools import islice, chain, groupby, accumulate

# 매 first 100 records 만
head = list(islice(read_jsonl("big.jsonl"), 100))

# 매 multiple sources 의 concat
combined = chain(read_jsonl("a.jsonl"), read_jsonl("b.jsonl"))

# 매 group by user
sorted_records = sorted(combined, key=lambda r: r["user_id"])
for user_id, group in groupby(sorted_records, key=lambda r: r["user_id"]):
    handle_user(user_id, list(group))

Pattern 3: Async iteration (2026)

import asyncio
import httpx

async def fetch_pages(urls: list[str]):
    async with httpx.AsyncClient() as client:
        async def fetch(url):
            r = await client.get(url)
            return url, r.text
        for coro in asyncio.as_completed([fetch(u) for u in urls]):
            yield await coro

async def main():
    async for url, html in fetch_pages(URLS):
        print(url, len(html))

Pattern 4: Iterative refinement (algorithm)

def newton_sqrt(n: float, tol: float = 1e-10, max_iter: int = 50) -> float:
    x = n / 2
    for _ in range(max_iter):
        x_new = 0.5 * (x + n / x)
        if abs(x_new - x) < tol:
            return x_new
        x = x_new
    return x

Pattern 5: LLM agentic loop (2026)

from anthropic import Anthropic

client = Anthropic()

def agent_loop(task: str, max_iter: int = 10):
    history = [{"role": "user", "content": task}]
    for i in range(max_iter):
        msg = client.messages.create(
            model="claude-opus-4-7",
            max_tokens=4000,
            tools=TOOLS,
            messages=history,
        )
        history.append({"role": "assistant", "content": msg.content})
        if msg.stop_reason == "end_turn":
            return msg
        # tool_use → execute → observation → next iter
        observations = execute_tools(msg.content)
        history.append({"role": "user", "content": observations})
    raise RuntimeError("매 max_iter 의 reach")

Pattern 6: Sprint retrospective

def retro(sprint_data: dict) -> dict:
    return {
        "what_worked": sprint_data["green_items"],
        "what_didnt": sprint_data["red_items"],
        "experiments_next": [
            f"Try {hypothesis}" for hypothesis in sprint_data["new_ideas"]
        ],
        "metrics_delta": {
            k: sprint_data["after"][k] - sprint_data["before"][k]
            for k in sprint_data["before"]
        },
    }

Pattern 7: Bounded iteration with timeout

import time

def iterate_with_budget(items, budget_sec: float):
    start = time.time()
    for item in items:
        if time.time() - start > budget_sec:
            print(f"매 budget 매 expire — {item} 의 stop")
            return
        yield process(item)

매 결정 기준

상황	Approach
Large file processing	Generator (lazy).
Multiple I/O calls	Async iteration.
CPU-bound loop	multiprocessing 또는 vectorize.
Numerical convergence	While + tolerance check.
Product development	2-week sprint + retrospective.
LLM agent	think-act-observe loop with max_iter cap.

기본값: Programming 매 generator-first; methodology 매 1-week iteration with measurable hypothesis.

🔗 Graph

• 부모: Agile
• 응용: Generator · Sprint
• Adjacent: Lean Startup

🤖 LLM 활용

언제: Agentic systems (think-act-observe), iterative refinement of code via LLM feedback, sprint planning summaries. 언제 X: Single-shot generation, tasks where each iteration is 1+ hours of human work (cycle too slow).

❌ 안티패턴

• Eager when lazy works: list(huge_generator) — 매 OOM.
• Unbounded loop: no max_iter — 매 infinite loop bug.
• No feedback in iteration: 매 build without measure — methodology 매 broken.
• Perfect first iteration: 매 ship at 70% — feedback 의 wait.

🧪 검증 / 중복

• Verified: PEP 234 (iterators), Eric Ries "Lean Startup" (2011), "Continuous Delivery" (Humble & Farley).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — full content covering both programming and methodology iteration with LLM agentic loop