Architecture

This library provides a lightweight, query-time knowledge-graph layer over an OMOP vocabulary database, with explicit separation between:

• graph access (nodes, edges, predicates),
• graph algorithms (traversal, pathfinding),
• path scoring and explanation, and
• presentation / inspection utilities.

omop-graph

omop-graph is a lightweight, opinionated knowledge-graph traversal and path-analysis library built on top of the OMOP vocabulary model.

It provides:

• a stable KnowledgeGraph façade over OMOP concepts and relationships
• flexible graph traversal (forward, backward, bidirectional)
• path discovery and ranking with transparent scoring
• traceable explanations of why one path is preferred over another
• multiple rendering backends (text, HTML, Mermaid)

The library is designed for:

• interactive analysis (Jupyter)
• reproducible research
• downstream tooling (NLP pipelines, ontology alignment, curation tools)

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Installation

pip install omop-graph

Core Concepts

KnowledgeGraph

KnowledgeGraph is the main entry point. It wraps an existing SQLAlchemy session connected to an OMOP vocabulary schema. kg-core assumes OMOP semantics and tables.

from from omop_graph.graph.kg import KnowledgeGraph

Nodes and Edges

Nodes are OMOP Concepts; Edges are OMOP Concept_Relationships

Relationships are classified into semantic kinds:

• ONTOLOGICAL
• MAPPING
• ATTRIBUTE
• VERSIONING
• METADATA

This classification drives traversal and scoring.

Traversal, Paths and Scoring

You can:

• expand neighbourhoods
• extract subgraphs
• trace traversal decisions
• control which relationship kinds are followed
• discover multiple candidate paths between concepts and rank them
• render simple HTML cards for easy interactive exploration

from omop_graph.graph.scoring import find_shortest_paths
from omop_graph.graph.edges import PredicateKind

ingredient = kg.concept_id_by_code("RxNorm", "6809") # Metformin
drug = kg.concept_id_by_code("RxNorm", "860975") # Metformin 500 MG Oral Tablet

kg.concept_view(drug) # ConceptView(id=40163924, RxNorm:860975, name='24 HR metformin hydrochloride 500 MG Extended Release Oral Tablet')
kg.concept_view(ingredient) # ConceptView(id=1503297, RxNorm:6809, name='metformin')

paths, trace = find_shortest_paths(
    kg,
    source=drug,
    target=ingredient,
    predicate_kinds={
        PredicateKind.ONTOLOGICAL,
        PredicateKind.MAPPING,
    },
    max_depth=6,
    traced=True,
)

ranked = rank_paths(kg, paths)

paths = kg.find_shortest_paths(
    source=a,
    target=b,
    max_depth=6,
)
ranked = kg.rank_paths(paths)

Rendering

Outputs can be rendered as:

• plain text (CLI / logs)
• HTML (Jupyter)
• Mermaid diagrams

Rendering auto-detects the environment.

from IPython.display import HTML, display
from kg_core.render import render_trace

display(HTML(render_trace(kg, trace)))

Project Structure

omop_graph/
├── graph/          # graph logic, traversal, paths, scoring
├── render/         # HTML / text / Mermaid renderers
├── reasoning/      # Ontology traversal methods for specific reasoner tasks
├────── resolvers/  # Resolve labels for exact / fuzzy / synonym matches - TODO: embedding matches
├────── phenotypes/ # Set operations to build efficient hierarchical groupings for reasoning
├── api.py          # stable public API surface
└── db/             # session helpers