Python API Reference¶

Python bindings for OntoLogos via PyPI ontologos.

Tutorial: Python guide. Install channels: Install and channels.

Install¶

pip install ontologos
pip install 'ontologos[pandas]'   # optional DataFrame export
pip install 'ontologos[polars]'    # optional polars export

Requires Python 3.10+.

Profiles¶

Published on PyPI 1.0.0: "auto", "rdfs", "rl", "el", "dl", and "swrl" are production-supported. "alc" and "dl-preview" are preview only.

Full matrix: Profile stability.

`Reasoner`¶

from ontologos import Reasoner

Constructor¶

Reasoner(path=None, ontology=None, profile="auto", incremental=False, budget_secs=None)

Exactly one of path or ontology is required.

Parameter	Description
`path`	Path to `.owl`, `.rdf`, `.ttl`, or `.ofn`
`ontology`	In-memory ontology from `OntologyBuilder` or JSON
`profile`	`"auto"`, `"rdfs"`, `"rl"`, `"el"`, `"dl"`, `"swrl"`, `"alc"`, `"dl-preview"`
`incremental`	Reuse session across `classify()` calls after mutations
`budget_secs`	Wall-clock budget for DL consistency/classify

Invalid profile strings raise RuntimeError.

Methods¶

Method	Returns	Description
`classify()`	`dict`	Run profile engine; taxonomy or materialization report
`check_consistency()`	`dict`	`{"consistent": bool, "complete": bool}` — prefer over `is_consistent` for DL
`is_consistent()`	`bool`	Convenience; raises `IncompleteReasoningError` when incomplete
`is_entailed(...)`	`bool`	Entailment for `SubClassOf`, `ClassAssertion`, or `ObjectPropertyAssertion`
`query(query: str)`	`list[dict]`	OWL QL conjunctive query (auto-classifies if needed)
`explain()`	`dict`	Proof graph (EL full; RL/RDFS asserted-only)
`add_subclass_of(sub, sup)`	`None`	Incremental mutation
`remove_subclass_of(sub, sup)`	`None`	Incremental mutation
`add_axiom_json(axiom)`	`None`	Add axiom from JSON dict

`classify()` return shapes¶

Profile family	Keys (typical)
EL / DL / ALC	`status: "classified"`, `subsumption_count`, `subsumptions`
RDFS / RL	`status: "classified"`, `initial_axiom_count`, `final_axiom_count`, `inferred_axioms`

`is_entailed` forms¶

is_entailed(sub, sup) — SubClassOf
is_entailed(individual=..., class_=...) — ClassAssertion
is_entailed(subject=..., property=..., object=...) — ObjectPropertyAssertion

Properties¶

Property	Description
`taxonomy`	Last taxonomy dict after EL/DL `classify()`
`parse_meta`	Parser metadata dict after file load (`warnings`, `mapped_axiom_count`, …)

`OntologyBuilder`¶

from ontologos import OntologyBuilder

b = OntologyBuilder()
b.add_class("http://example.org/Food")
b.add_class("http://example.org/Pizza")
b.subclass_of("http://example.org/Pizza", "http://example.org/Food")
ontology = b.build()
reasoner = Reasoner(ontology=ontology, profile="el")

Builder methods: add_class, individual, object_property, subclass_of, subproperty_of, property_domain, property_range, class_assertion, object_property_assertion, build().

`Ontology`¶

Method	Description
`from_json(str)`	Load JSON snapshot (v2 or v3)
`from_json_with_limits(str, *, max_json_bytes=..., ...)`	Load with resource caps
`from_dict(dict)`	Load from Python dict
`to_json()` / `to_dict()`	Serialize
`axiom_count` / `entity_count`	Size getters

Export functions¶

from ontologos import Reasoner, subsumptions_to_pandas, subsumptions_to_polars

# EL taxonomy export (requires pizza.owl)
report = Reasoner(path="pizza.owl", profile="el").classify()
df = subsumptions_to_pandas(report)   # requires ontologos[pandas]

There is no taxonomy_dataframe() method — use subsumptions_to_pandas(report) or subsumptions_to_polars(report).

Exceptions¶

from ontologos import ParseError, ResourceLimitError, IncompleteReasoningError

Exception	When
`ParseError`	Parser / JSON serialization failures
`ResourceLimitError`	DL/ALC preview or resource caps exceeded
`IncompleteReasoningError`	`is_consistent()` when check incomplete; DL budget limits
`RuntimeError`	Unsupported profile, invalid constructor args, other failures

Quick start¶

curl -L -o family.owl \
  https://raw.githubusercontent.com/eddiethedean/ontologos/main/benchmarks/data/family.owl

from ontologos import Reasoner

report = Reasoner(path="family.owl", profile="rl").classify()
print(report)

Limitations¶

Not thread-safe — one Reasoner per thread
Subproperty / property-value lookups: CLI and Rust facade only
Validate DL results on your corpus before production — see DL API and Evaluator scope