Classificação hierárquica

Classifica documentos através de hierarquias profundas de patentes, produtos de varejo, biomedicina e código-fonte usando busca em feixe paralela sobre as probabilidades de Choice do TypeSafe.

Muitos dados existem como hierarquias estruturadas, como taxonomias, hierarquias de sistema de arquivos, estruturas de sites, bases de código, organogramas, ontologias biológicas, habilidades de LLM, políticas de moderação etc. O objetivo da Classificação Hierárquica é percorrer a hierarquia até o nó folha correto, que é a classificação final. Isso é um encaixe perfeito para a primitiva Choice do typesafe. Encontramos a folha mais provável classificando o documento em cada nó (começando pela raiz) e então avançando iterativamente para o próximo nó mais provável até terminarmos em uma folha (Busca Gulosa).

A natureza paralela da API também nos permite explorar vários caminhos com perguntas paralelas, usando a Busca em Feixe para melhorar o desempenho. As chamadas à API do TypeSafe do cookbook avaliam simultaneamente K caminhos da hierarquia. A busca em feixe mantém os melhores K caminhos por uma probabilidade geométrica de aresta: product(edge_probabilities) ** (1 / decisions), e poda o resto. A probabilidade é normalizada pelo comprimento para que folhas rasas e profundas sejam comparadas de forma justa.

Decompor o problema em uma hierarquia assim tem benefícios próprios:

• Observabilidade
  • identifique em quais nós suas classificações erradas ocorrem mais
  • meça o número de vezes que cada nó e cada aresta é percorrido
• Testabilidade
  • teste unitariamente e meça o impacto de atualizações da hierarquia no desempenho da classificação
• 

Hierarquias usadas neste cookbook

• CPC 2026.05: matéria de patente, de grandes seções de tecnologia a invenções específicas.
• Shopify 2026-02: categorias de produtos de varejo, de departamentos de loja a tipos específicos de produto.
• MeSH 2026: assuntos biomédicos, de domínios amplos a condições específicas. O MeSH é um DAG, então um descritor pode aparecer sob vários pais; esta demo expande seus caminhos oficiais de número de árvore.
• Arquivos do CookSafe: a hierarquia do repositório de cookbooks do TypeSafe, buscada de pastas a arquivos-fonte.

Métodos

• Busca gulosa: escolha o filho de maior probabilidade e descarte todas as alternativas. Um erro cometido cedo não pode ser recuperado.
• Busca em feixe: retenha K caminhos plausíveis e classifique toda fronteira em paralelo. Evidência mais profunda pode reparar uma decisão ambígua tomada cedo. A folha do caminho com a maior probabilidade geométrica é a classificação final.
• Choice do TypeSafe: cada nó é uma pergunta Choice cuja distribuição de probabilidade completa são suas arestas. Cada caminho do feixe roda como perguntas paralelas, então exploração extra acrescenta pouca latência real.
• Fórmula:
  • path_score = product(edge_probabilities) ** (1 / decisions)
    • usada para podar e comparar caminhos
  • separation = top_path_score / second_path_score
    • métrica útil, mas não usada para podar
    • a razão compara a média geométrica do caminho principal com seu rival mais próximo.
      • Perto de 1× é ambíguo
      • Uma razão grande indica separação clara.
• Notas sobre métricas:
  • uma métrica diferente como min(top_prob/second_top_prob), que otimizaria para caminhos com decisões muito claras em cada nó.
  • use exp(mean(log(probs))) em vez de product(edge_probabilities) ** (1 / decisions) para evitar erros de precisão em hierarquias muito profundas (ex.: >10 camadas)

Carregue e visualize as hierarquias de exemplo

Esses helpers baixam fontes de taxonomia fixadas, as transformam em árvores de filhos diretos, e renderizam cada percurso de busca como um SVG estático.

import html
import os
import shutil
import textwrap
import urllib.request
from collections import defaultdict
from concurrent.futures import ThreadPoolExecutor
from pathlib import Path
from typing import NamedTuple, TypeAlias
from xml.etree import ElementTree
from zipfile import ZipFile

from cooksafe import JsonCache
from IPython.display import Markdown, display
from typesafe_sdk import Choice, RetryPolicy, TypeSafeClient

Tree: TypeAlias = dict[str, "Tree"]

class Hierarchy(NamedTuple):
    """One query and a complete hierarchy.

    :param slug: filename-safe taxonomy name.
    :param name: display name.
    :param version: pinned dataset version.
    :param source_url: hierarchy source.
    :param node_count: number of loaded hierarchy nodes.
    :param document: unstructured text classified by TypeSafe.
    :param expected_leaf: expected final classification.
    :param tree: nested direct-child menus.
    """

    slug: str
    name: str
    version: str
    source_url: str
    node_count: int
    document: str
    expected_leaf: str
    tree: Tree

CPC_URL = (
    "https://www.cooperativepatentclassification.org/sites/default/files/"
    "cpc/bulk/CPCSchemeXML202605.zip"
)
SHOPIFY_URL = (
    "https://raw.githubusercontent.com/Shopify/product-taxonomy/"
    "v2026-02/dist/en/categories.txt"
)
MESH_URL = "https://nlmpubs.nlm.nih.gov/projects/mesh/MESH_FILES/xmlmesh/desc2026.zip"
MESH_CATEGORIES = {
    "A": "Anatomy",
    "B": "Organisms",
    "C": "Diseases",
    "D": "Chemicals and Drugs",
    "E": "Analytical, Diagnostic and Therapeutic Techniques, and Equipment",
    "F": "Psychiatry and Psychology",
    "G": "Phenomena and Processes",
    "H": "Disciplines and Occupations",
    "I": "Anthropology, Education, Sociology, and Social Phenomena",
    "J": "Technology, Industry, and Agriculture",
    "K": "Humanities",
    "L": "Information Science",
    "M": "Named Groups",
    "N": "Health Care",
    "V": "Publication Characteristics",
    "Z": "Geographicals",
}

def _download(url: str, path: Path) -> Path:
    """Download a pinned dataset once.

    :param url: official dataset URL.
    :param path: local cache path.
    :returns: local dataset path.
    """

    if path.exists():
        return path
    path.parent.mkdir(parents=True, exist_ok=True)
    temporary_path: Path = path.with_suffix(path.suffix + ".tmp")
    request = urllib.request.Request(
        url, headers={"User-Agent": "typesafe-taxonomy/1.0"}
    )
    with urllib.request.urlopen(request, timeout=120) as response:
        with temporary_path.open("wb") as file:
            shutil.copyfileobj(response, file)
    temporary_path.replace(path)
    return path

def _insert(tree: Tree, path: tuple[str, ...]) -> None:
    subtree_value: Tree = tree
    for label in path:
        subtree_value = subtree_value.setdefault(label, {})

def _cpc_title(item: ElementTree.Element) -> str:
    class_title: ElementTree.Element | None = item.find("class-title")
    if class_title is None:
        return ""
    return " ".join(" ".join(class_title.itertext()).split())

def _load_cpc(path: Path) -> tuple[Tree, int]:
    titles: dict[str, str] = {}
    levels: dict[str, int] = {}
    parent_by_symbol: dict[str, str] = {}
    children_by_symbol: defaultdict[str, list[str]] = defaultdict(list)

    def visit(item: ElementTree.Element, parent_symbol: str | None) -> None:
        symbol: str | None = item.findtext("classification-symbol")
        next_parent: str | None = parent_symbol
        if symbol:
            title: str = _cpc_title(item)
            if title:
                titles[symbol] = title
            levels[symbol] = min(levels.get(symbol, 99), int(item.attrib["level"]))
            if (
                parent_symbol
                and parent_symbol != symbol
                and symbol not in parent_by_symbol
            ):
                parent_by_symbol[symbol] = parent_symbol
                children_by_symbol[parent_symbol].append(symbol)
            next_parent = symbol
        for child in item.findall("classification-item"):
            visit(child, next_parent)

    with ZipFile(path) as zip_file:
        names = sorted(
            name
            for name in zip_file.namelist()
            if name.startswith("cpc-scheme-") and name.endswith(".xml")
        )
        for name in names:
            root = ElementTree.fromstring(zip_file.read(name))
            for item in root.findall("classification-item"):
                visit(item, None)

    labels: dict[str, str] = {
        symbol: f"{symbol} {titles.get(symbol, '')}".strip() for symbol in levels
    }

    def build(symbol: str) -> Tree:
        return {
            labels[child]: build(child) for child in children_by_symbol.get(symbol, [])
        }

    root_symbols: list[str] = sorted(
        symbol for symbol, level in levels.items() if level == 2
    )
    tree: Tree = {labels[symbol]: build(symbol) for symbol in root_symbols}
    return tree, len(labels)

def _load_shopify(path: Path) -> tuple[Tree, int]:
    tree: Tree = {}
    category_count: int = 0
    for line in path.read_text().splitlines():
        if not line or line.startswith("#"):
            continue
        _, path_text = line.split(" : ", maxsplit=1)
        category_path: tuple[str, ...] = tuple(path_text.strip().split(" > "))
        _insert(tree, category_path)
        category_count += 1
    return tree, category_count

def _load_mesh(path: Path) -> tuple[Tree, int]:
    """Load every official MeSH tree-number path.

    A descriptor may have multiple tree numbers because MeSH is a DAG. Expanding
    those positions into paths makes it usable by the tree-oriented beam search.

    :param path: MeSH descriptor XML ZIP.
    :returns: expanded tree and position count.
    """

    with ZipFile(path) as zip_file:
        root: ElementTree.Element = ElementTree.fromstring(
            zip_file.read("desc2026.xml")
        )
    names_by_tree_number: dict[str, str] = {
        tree_number.text: descriptor_record.findtext("DescriptorName/String", "")
        for descriptor_record in root.findall("DescriptorRecord")
        for tree_number in descriptor_record.findall("TreeNumberList/TreeNumber")
        if tree_number.text
    }
    tree: Tree = {}
    for tree_number in sorted(names_by_tree_number):
        parts: list[str] = tree_number.split(".")
        prefixes: list[str] = [
            ".".join(parts[:index]) for index in range(1, len(parts) + 1)
        ]
        category_code: str = tree_number[0]
        category_path: tuple[str, ...] = (
            f"{category_code} {MESH_CATEGORIES[category_code]}",
            *(f"{prefix} {names_by_tree_number[prefix]}" for prefix in prefixes),
        )
        _insert(tree, category_path)
    position_count: int = len(names_by_tree_number) + len(tree)
    return tree, position_count

CODEBASE_SNAPSHOT = Path("codebase_files.txt")

def _load_codebase(path: Path) -> tuple[Tree, int]:
    """Load the frozen CookSafe source-file hierarchy.

    The listing is a snapshot of the repository's source files in the order a walk found them,
    taken when this cookbook was rendered, rather than a walk of whatever tree the cookbook
    happens to sit in. A live walk makes the taxonomy -- and every number derived from it --
    depend on the reader's checkout, including untracked scratch files, so the shipped cache
    stops describing the same tree. Line order is significant: sibling options are asked in the
    order they appear here, so it is part of the question, not presentation.

    :param path: file holding one repository-relative source path per line.
    :returns: nested file tree and node count.
    """

    tree: Tree = {}
    node_paths: set[tuple[str, ...]] = set()
    for line in path.read_text(encoding="utf-8").splitlines():
        if not line.strip():
            continue
        hierarchy_path: tuple[str, ...] = ("CookSafe", *line.split("/"))
        _insert(tree, hierarchy_path)
        node_paths.update(
            hierarchy_path[:index] for index in range(1, len(hierarchy_path) + 1)
        )
    return tree, len(node_paths)

def load_hierarchies(data_directory: Path = Path("datasets")) -> tuple[Hierarchy, ...]:
    """Load three public taxonomies and one frozen code hierarchy.

    :param data_directory: cache directory for official raw files.
    :returns: CPC, Shopify, MeSH, and CookSafe examples.
    """

    cpc_tree, cpc_nodes = _load_cpc(
        _download(CPC_URL, data_directory / "CPCSchemeXML202605.zip")
    )
    shopify_tree, shopify_nodes = _load_shopify(
        _download(SHOPIFY_URL, data_directory / "shopify_categories_2026-02.txt")
    )
    mesh_tree, mesh_nodes = _load_mesh(
        _download(MESH_URL, data_directory / "mesh_descriptors_2026.zip")
    )
    codebase_tree, codebase_nodes = _load_codebase(CODEBASE_SNAPSHOT)
    return (
        Hierarchy(
            slug="cpc",
            name="CPC patents",
            version="2026.05",
            source_url=CPC_URL,
            node_count=cpc_nodes,
            document=(
                "Patent abstract: a freestanding structural wooden perch for poultry or "
                "pet birds. The elevated roost has crossbars sized for bird feet and mounts "
                "inside an aviary."
            ),
            expected_leaf="A01K31/12 Perches for poultry or birds, e.g. roosts",
            tree=cpc_tree,
        ),
        Hierarchy(
            slug="shopify",
            name="Shopify products",
            version="2026-02",
            source_url=SHOPIFY_URL,
            node_count=shopify_nodes,
            document=(
                "Furniture listing: a wall-mounted window shelf bed. This padded floating shelf "
                "uses suction cups and a washable cushion as a sunny perch for one cat."
            ),
            expected_leaf="Cat Window Beds & Perches",
            tree=shopify_tree,
        ),
        Hierarchy(
            slug="mesh",
            name="MeSH biomedical subjects",
            version="2026",
            source_url=MESH_URL,
            node_count=mesh_nodes,
            document=(
                "Clinical abstract: Crohn disease with transmural ileocolonic inflammation, "
                "skip lesions, abdominal pain, and chronic diarrhea. Colonoscopy showed "
                "cobblestoning and biopsy found noncaseating granulomas; treatment with "
                "infliximab produced remission."
            ),
            expected_leaf="C06.405.469.432.500 Crohn Disease",
            tree=mesh_tree,
        ),
        Hierarchy(
            slug="codebase",
            name="CookSafe files",
            version="snapshot 2026-08-06",
            source_url=str(CODEBASE_SNAPSHOT),
            node_count=codebase_nodes,
            document=(
                "Developer search: find the experimental Python module under x/eugene that "
                "implements BM25, dense, and fused retrievers for legal RAG."
            ),
            expected_leaf="retrievers.py",
            tree=codebase_tree,
        ),
    )

NODE_W, NODE_H = 300, 38
COL_W, ROW_H = 360, 50
PAD_X = 28
EDGE_TOP_K = 5

def subtree(tree: Tree, path: tuple[str, ...]) -> Tree:
    """Return the direct-child menu below ``path``.

    :param tree: taxonomy root.
    :param path: path from the taxonomy root.
    :returns: child mapping at the path.
    """

    subtree_value: Tree = tree
    for label in path:
        subtree_value = subtree_value[label]
    return subtree_value

def _escape(value: object) -> str:
    return html.escape(str(value), quote=True)

def _truncate(value: str, length: int = 33) -> str:
    return value if len(value) <= length else value[: length - 1] + "…"

def _build_nodes(hierarchy: Hierarchy, result: dict) -> dict:
    records: dict[tuple[str, ...], dict] = {
        tuple(record["parent"]): record for record in result["records"]
    }
    best_path: tuple[str, ...] = tuple(result["beam"][0]["path"])
    greedy_path: tuple[str, ...] = tuple(result["greedy"]["path"])
    retained: set[tuple[str, ...]] = {tuple(path) for path in result["retained_paths"]}

    def grow(path: tuple[str, ...]) -> list[dict]:
        record: dict | None = records.get(path)
        if record is None:
            return []
        children: list[dict] = []
        probabilities: dict[str, float] = record["probabilities"]
        ranked: list[tuple[str, float]] = sorted(
            probabilities.items(), key=lambda item: item[1], reverse=True
        )
        shown_labels: set[str] = {label for label, _ in ranked[:EDGE_TOP_K]}
        shown_labels.update(
            label
            for label, _ in ranked
            if path + (label,) in retained
            or path + (label,) == best_path[: len(path) + 1]
            or path + (label,) == greedy_path[: len(path) + 1]
        )
        for label, probability in ranked:
            if label not in shown_labels:
                continue
            child_path: tuple[str, ...] = path + (label,)
            on_best_path: bool = child_path == best_path[: len(child_path)]
            on_greedy_path: bool = child_path == greedy_path[: len(child_path)]
            kind: str = (
                "winner"
                if on_best_path
                else "greedy"
                if on_greedy_path
                else "beam"
                if child_path in retained
                else "alt"
            )
            children.append(
                {
                    "label": label,
                    "probability": probability,
                    "kind": kind,
                    "children": grow(child_path),
                }
            )
        return children

    return {
        "label": hierarchy.name,
        "probability": None,
        "kind": "root",
        "children": grow(()),
    }

def _layout(root: dict) -> tuple[int, int]:
    rows: list[int] = [0]
    maximum_depth: list[int] = [0]

    def walk(node: dict, depth: int) -> None:
        node["depth"] = depth
        maximum_depth[0] = max(maximum_depth[0], depth)
        if node["children"]:
            for child in node["children"]:
                walk(child, depth + 1)
            node["row"] = (node["children"][0]["row"] + node["children"][-1]["row"]) / 2
        else:
            node["row"] = rows[0]
            rows[0] += 1

    walk(root, 0)
    return maximum_depth[0], rows[0]

def render_svg(hierarchy: Hierarchy, result: dict, path: Path) -> None:
    """Write a standalone traversal SVG matching the Customer_ProdX visual language.

    :param hierarchy: taxonomy demonstration.
    :param result: beam-search result from the notebook.
    :param path: output SVG path.
    """

    root: dict = _build_nodes(hierarchy, result)
    maximum_depth, row_count = _layout(root)
    document_lines: list[str] = textwrap.wrap(
        hierarchy.document,
        width=105,
        break_long_words=False,
        break_on_hyphens=False,
    ) or [""]
    document_y: int = 124
    greedy_y: int = document_y + (len(document_lines) - 1) * 21 + 34
    beam_y: int = greedy_y + 25
    method_y: int = beam_y + 29
    legend_y: int = method_y + 23
    header_height: int = legend_y + 32
    width: int = PAD_X * 2 + maximum_depth * COL_W + NODE_W
    height: int = header_height + max(row_count, 1) * ROW_H + 34
    edges: list[str] = []
    nodes: list[str] = []

    def node_x(node: dict) -> float:
        return PAD_X + node["depth"] * COL_W

    def node_y(node: dict) -> float:
        return header_height + node["row"] * ROW_H

    def walk(node: dict) -> None:
        x_value, y_value = node_x(node), node_y(node)
        for child in node["children"]:
            child_x, child_y = node_x(child), node_y(child)
            x1, y1 = x_value + NODE_W, y_value + NODE_H / 2
            x2, y2 = child_x, child_y + NODE_H / 2
            bend: float = COL_W * 0.38
            edges.append(
                f'<path class="edge {child["kind"]}" '
                f'd="M{x1:.0f},{y1:.0f} C{x1 + bend:.0f},{y1:.0f} '
                f'{x2 - bend:.0f},{y2:.0f} {x2:.0f},{y2:.0f}"/>'
            )
            edges.append(
                f'<text class="prob" x="{x2 - 7:.0f}" y="{y2 - 5:.0f}" '
                f'text-anchor="end">{child["probability"]:.2f}</text>'
            )
            walk(child)

        kind: str = node["kind"]
        label: str = _truncate(node["label"], 40)
        nodes.append(
            f'<g class="node {kind}"><title>{_escape(node["label"])}</title>'
            f'<rect x="{x_value:.0f}" y="{y_value:.0f}" width="{NODE_W}" '
            f'height="{NODE_H}" rx="7"/>'
            f'<text x="{x_value + 11:.0f}" y="{y_value + 24:.0f}">'
            f"{_escape(label)}</text></g>"
        )

    walk(root)
    best: dict = result["beam"][0]
    best_path: tuple[str, ...] = tuple(best["path"])
    greedy_path: tuple[str, ...] = tuple(result["greedy"]["path"])
    beam_leaf: str = best_path[-1] if best_path else "no leaf"
    greedy_leaf: str = greedy_path[-1] if greedy_path else "no leaf"
    beam_width: int = result["beam_width"]
    separation_ratio: float = result["separation_ratio"]
    document_text: str = "".join(
        f'<text class="document" x="24" y="{document_y + index * 21}">'
        f"{_escape(line)}</text>"
        for index, line in enumerate(document_lines)
    )
    separation_text: str = (
        ">999×" if separation_ratio > 999 else f"{separation_ratio:.2f}×"
    )

    svg: str = f'''<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 {width} {height}"
  width="{width}" height="{height}" role="img" aria-label="{_escape(hierarchy.name)} taxonomy beam search">
<style>
  .bg {{ fill:#f6f7fb }}
  text {{ font-family:ui-monospace,"SF Mono",Menlo,Consolas,monospace }}
  .eyebrow {{ font-size:14px; font-weight:700; letter-spacing:1.2px; fill:#4f46e5 }}
  .title {{ font:700 28px system-ui,-apple-system,"Segoe UI",sans-serif; fill:#181b28 }}
  .document-label {{ font:700 12px system-ui,-apple-system,"Segoe UI",sans-serif; letter-spacing:1px; fill:#777c91 }}
  .document {{ font:500 17px system-ui,-apple-system,"Segoe UI",sans-serif; fill:#303449 }}
  .copy {{ font-size:14px; fill:#5c6178 }}
  .result {{ font-size:14px; font-weight:700 }}
  .greedy-result {{ fill:#c2410c }}
  .beam-result {{ fill:#15803d }}
  .edge {{ fill:none; stroke:#c9cee0; stroke-width:2 }}
  .edge.winner {{ stroke:#15803d; stroke-width:2.5 }}
  .edge.greedy {{ stroke:#ea580c; stroke-width:2.5 }}
  .edge.beam {{ stroke:#4f46e5; stroke-width:2.2 }}
  .edge.alt {{ opacity:.48 }}
  .prob {{ font-size:12px; font-weight:600; fill:#5c6178 }}
  .node rect {{ stroke-width:1.7 }}
  .node text {{ font-size:13px }}
  .node.root rect {{ fill:#f0f2f8; stroke:#e2e5f0 }}
  .node.root text {{ fill:#5c6178 }}
  .node.winner rect {{ fill:#e4f5ea; stroke:#15803d }}
  .node.winner text {{ fill:#15803d; font-weight:700 }}
  .node.greedy rect {{ fill:#fff0e8; stroke:#ea580c }}
  .node.greedy text {{ fill:#c2410c; font-weight:700 }}
  .node.beam rect {{ fill:#ecebfd; stroke:#4f46e5 }}
  .node.beam text {{ fill:#181b28 }}
  .node.alt rect {{ fill:#fff; stroke:#e2e5f0; stroke-dasharray:3 3 }}
  .node.alt text {{ fill:#5c6178 }}
</style>
<rect class="bg" width="{width}" height="{height}" rx="14"/>
<text class="eyebrow" x="24" y="32">TYPESAFE · {hierarchy.name.upper()} · {hierarchy.version.upper()} · {hierarchy.node_count:,} NODES</text>
<text class="title" x="24" y="69">Greedy vs parallel beam search</text>
<text class="document-label" x="24" y="99">DOCUMENT</text>
{document_text}
<text class="result greedy-result" x="24" y="{greedy_y}">GREEDY TOP-1 → {_escape(_truncate(greedy_leaf, 105))}</text>
<text class="result beam-result" x="24" y="{beam_y}">BEAM K={beam_width} → {_escape(_truncate(beam_leaf, 105))}</text>
<text class="copy" x="24" y="{method_y}">parallel sibling Choices → keep {beam_width} by geometric mean p → top/second = {separation_text}</text>
<text class="copy" x="24" y="{legend_y}">orange = greedy   green = beam winner   purple = retained beam   dashed = pruned</text>
{"".join(edges)}{"".join(nodes)}
</svg>'''
    path.write_text(svg)

Implemente a busca gulosa e a busca em feixe

Cada conjunto de irmãos vira uma pergunta Choice na próxima seção, que também implementa as duas estratégias de percurso e guarda as probabilidades de que os diagramas estáticos precisam.

HIERARCHIES = load_hierarchies()
MODEL, BEAM_WIDTH, MAX_DEPTH, EPSILON = "jev-1.12", 3, 12, 1e-9
client = TypeSafeClient(
    api_key=os.environ["TYPESAFE_API_KEY"],
    retry=RetryPolicy(max_retries=5, backoff_initial=1.0, backoff_max=20.0),
)
json_cache = JsonCache(Path("json_cache.json"))

@json_cache
def choose(state: str, labels: tuple[str, ...]) -> dict[str, float]:
    """Ask one atomic direct-child question and return its distribution."""
    if len(labels) == 1:
        return {labels[0]: 1.0}
    question, keys = child_question(labels)
    response = client.system_one(
        state=state, questions={"child": question}, model=MODEL
    )
    probabilities = response.answers["child"].probabilities
    return {label: probabilities[key] for key, label in keys.items()}

def child_question(labels: tuple[str, ...]) -> tuple[Choice, dict[str, str]]:
    """Build the direct-child Choice and its reversible option mapping."""
    keys = {f"c{i}": label for i, label in enumerate(labels)}
    question = Choice(
        instructions="Which direct child category best matches this document?",
        criteria=keys,
    )
    return question, keys

def extend_candidate(
    candidate: dict, label: str, probabilities: dict[str, float]
) -> dict:
    """Append one edge and recompute its geometric-mean path score."""
    is_decision: bool = len(probabilities) > 1
    # Use log space for very deep trees to avoid floating-point precision loss.
    probability_product: float = candidate["probability_product"] * (
        max(probabilities[label], EPSILON) if is_decision else 1.0
    )
    decision_count: int = candidate["decision_count"] + is_decision
    return {
        "path": candidate["path"] + (label,),
        "probability_product": probability_product,
        "decision_count": decision_count,
        "score": probability_product ** (1 / decision_count) if decision_count else 1.0,
    }

def choice_record(path: tuple[str, ...], probabilities: dict[str, float]) -> dict:
    """Package one sibling decision for the traversal diagram."""
    return {"parent": path, "probabilities": probabilities}

def beam_search(hierarchy: Hierarchy) -> dict:
    """Parallel width-three beam search using geometric-mean probability."""
    beam = [{"path": (), "probability_product": 1.0, "decision_count": 0, "score": 1.0}]
    records, retained_paths = [], {()}

    for _ in range(MAX_DEPTH):
        expandable = [
            candidate
            for candidate in beam
            if subtree(hierarchy.tree, candidate["path"])
        ]
        finished = [
            candidate
            for candidate in beam
            if not subtree(hierarchy.tree, candidate["path"])
        ]
        if not expandable:
            break
        with ThreadPoolExecutor(max_workers=BEAM_WIDTH) as executor:
            distributions = list(
                executor.map(
                    lambda candidate: choose(
                        hierarchy.document,
                        tuple(subtree(hierarchy.tree, candidate["path"])),
                    ),
                    expandable,
                )
            )

        expanded = []
        round_records = []
        for candidate, probabilities in zip(expandable, distributions, strict=True):
            round_records.append(choice_record(candidate["path"], probabilities))
            candidate_expanded = []
            for label in probabilities:
                candidate_expanded.append(
                    extend_candidate(candidate, label, probabilities)
                )
            expanded.extend(candidate_expanded)
        beam = sorted(
            finished + expanded,
            key=lambda candidate: candidate["score"],
            reverse=True,
        )[:BEAM_WIDTH]
        retained_paths.update(candidate["path"] for candidate in beam)
        records.extend(round_records)

    beam = sorted(beam, key=lambda candidate: candidate["score"], reverse=True)
    return {
        "beam": beam,
        "records": records,
        "retained_paths": sorted(retained_paths, key=lambda path: (len(path), path)),
    }

def greedy_search(hierarchy: Hierarchy) -> dict:
    """Follow only the locally highest-probability child."""
    path, probability_product, decision_count, records = (), 1.0, 0, []
    for _ in range(MAX_DEPTH):
        labels = tuple(subtree(hierarchy.tree, path))
        if not labels:
            break
        probabilities = choose(hierarchy.document, labels)
        records.append(choice_record(path, probabilities))
        label = max(probabilities, key=probabilities.get)
        if len(probabilities) > 1:
            probability_product *= max(probabilities[label], EPSILON)
            decision_count += 1
        path += (label,)
    score: float = (
        probability_product ** (1 / decision_count) if decision_count else 1.0
    )
    return {"path": path, "score": score, "records": records}

def compare_searches(hierarchy: Hierarchy) -> dict:
    """Run beam and greedy, then merge their queried nodes for rendering."""
    result = beam_search(hierarchy)
    greedy = greedy_search(hierarchy)
    recorded_paths = {tuple(record["parent"]) for record in result["records"]}
    result["records"].extend(
        record
        for record in greedy["records"]
        if tuple(record["parent"]) not in recorded_paths
    )
    result["greedy"] = greedy
    result["beam_width"] = BEAM_WIDTH
    top_score: float = result["beam"][0]["score"]
    second_score: float = result["beam"][1]["score"]
    result["separation_ratio"] = top_score / max(second_score, EPSILON)
    return result

Compare os métodos

Rode as duas estratégias em quatro exemplos rotulados, compare suas folhas com as classificações esperadas, e visualize as rotas que elas exploraram.

with ThreadPoolExecutor(max_workers=len(HIERARCHIES)) as executor:
    results = list(executor.map(compare_searches, HIERARCHIES))

rows: list[dict[str, str | int | bool]] = []
for hierarchy, result in zip(HIERARCHIES, results, strict=True):
    svg_path: Path = Path(f"{hierarchy.slug}_tree.svg")
    render_svg(hierarchy, result, svg_path)
    beam_path: tuple[str, ...] = tuple(result["beam"][0]["path"])
    greedy_path: tuple[str, ...] = tuple(result["greedy"]["path"])
    beam_leaf: str = beam_path[-1]
    greedy_leaf: str = greedy_path[-1]
    rows.append(
        {
            "hierarchy": hierarchy.name,
            "nodes": hierarchy.node_count,
            "expected leaf": hierarchy.expected_leaf,
            "greedy leaf": greedy_leaf,
            "beam K=3 leaf": beam_leaf,
            "greedy correct": greedy_leaf == hierarchy.expected_leaf,
            "beam correct": beam_leaf == hierarchy.expected_leaf,
            "mean p": f"{result['beam'][0]['score']:.2f}",
            "top/second": f"{result['separation_ratio']:.2f}×",
        }
    )

greedy_correct_count: int = sum(bool(row["greedy correct"]) for row in rows)
beam_correct_count: int = sum(bool(row["beam correct"]) for row in rows)
recovered_names: str = ", ".join(
    str(row["hierarchy"])
    for row in rows
    if not row["greedy correct"] and row["beam correct"]
)
table_lines: list[str] = [
    "| Hierarchy | Expected leaf | Greedy leaf | Beam K=3 leaf | Greedy correct | Beam correct |",
    "| --- | --- | --- | --- | --- | --- |",
]
table_lines.extend(
    "| "
    + " | ".join(
        (
            str(row["hierarchy"]),
            str(row["expected leaf"]),
            str(row["greedy leaf"]),
            str(row["beam K=3 leaf"]),
            "yes" if row["greedy correct"] else "no",
            "yes" if row["beam correct"] else "no",
        )
    )
    + " |"
    for row in rows
)
display(
    Markdown(
        "## Results\n\n"
        "Each example has a known expected leaf. "
        f"Beam search matched {beam_correct_count} of {len(rows)} expected leaves; "
        f"greedy search matched {greedy_correct_count} of {len(rows)}. "
        f"Keeping three paths recovered the expected classification for {recovered_names}.\n\n"
        + "\n".join(table_lines)
        + "\n\nThe diagrams show why the methods differ. Orange marks the greedy route, "
        "green marks the winning beam route, purple marks other retained paths, and "
        "dashed edges were pruned.\n\n"
        + "\n\n".join(
            f"### {hierarchy.name}\n\n![]({hierarchy.slug}_tree.svg)"
            for hierarchy in HIERARCHIES
        )
    )
)

Resultados

Cada exemplo tem uma folha esperada conhecida. A busca em feixe acertou 4 de 4 folhas esperadas; a busca gulosa acertou 2 de 4. Manter três caminhos recuperou a classificação esperada para CPC patents, Shopify products.

Os diagramas mostram por que os métodos diferem. Laranja marca a rota gulosa, verde marca a rota vencedora do feixe, roxo marca outros caminhos retidos, e arestas tracejadas foram podadas.

CPC patents

Shopify products

MeSH biomedical subjects

CookSafe files