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py-brickschema

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utility Python library

Features

  • wrapper around RDFlib providing syntactic sugar and simplified use
  • automatic loading of Brick ontology into graphs
  • embedded SPARQL server and web interface
  • built-in reasoning and inference (OWL, SHACL, RDFS)

Quickstart

The main Graph object is just a subclass of the excellent RDFlib Graph library, so all features on rdflib.Graph will also work here.

Brief overview of the main features of the brickschema package:

import brickschema

# creates a new rdflib.Graph with a recent version of the Brick ontology
# preloaded.
g = brickschema.Graph(load_brick=True)
# OR use the absolute latest Brick:
# g = brickschema.Graph(load_brick_nightly=True)
# OR create from an existing model
# g = brickschema.Graph(load_brick=True).from_haystack(...)

# load in data files from your file system
g.load_file("mbuilding.ttl")
# ...or by URL (using rdflib)
g.parse("https://brickschema.org/ttl/soda_brick.ttl", format="ttl")

# perform reasoning on the graph (edits in-place)
g.expand(profile="owlrl")
g.expand(profile="shacl") # infers Brick classes from Brick tags

# validate your Brick graph against built-in shapes (or add your own)
valid, _, resultsText = g.validate()
if not valid:
    print("Graph is not valid!")
    print(resultsText)

# perform SPARQL queries on the graph
res = g.query("""SELECT ?afs ?afsp ?vav WHERE  {
    ?afs    a       brick:Air_Flow_Sensor .
    ?afsp   a       brick:Air_Flow_Setpoint .
    ?afs    brick:isPointOf ?vav .
    ?afsp   brick:isPointOf ?vav .
    ?vav    a   brick:VAV
}""")
for row in res:
    print(row)

# start a blocking web server with an interface for performing
# reasoning + querying functions
g.serve("localhost:8080")
# now visit in http://localhost:8080

Features

Inference

brickschema makes it easier to employ reasoning on your graphs. Simply call the expand method on the Graph object with one of the following profiles:

  • "rdfs": RDFS reasoning
  • "owlrl": OWL-RL reasoning (using 1 of 3 implementations below)
  • "vbis": add VBIS tags to Brick entities
  • "tag": infer Brick classes from Brick tags
from brickschema import Graph

g = Graph(load_brick=True)
g.load_file("test.ttl")
g.expand(profile="owlrl")
print(f"Inferred graph has {len(g)} triples")

The package will automatically use the fastest available reasoning implementation for your system:

  • reasonable (fastest, Linux-only for now): pip install brickschema[reasonable]
  • Allegro (next-fastest, requires Docker): pip install brickschema[allegro]
  • OWLRL (default, native Python implementation): pip install brickschema

To use a specific reasoner, specify "reasonable", "allegrograph" or "owlrl" as the value for the backend argument to graph.expand.

Haystack Translation

brickschema can produce a Brick model from a JSON export of a Haystack model. Then you can use this package as follows:

import json
from brickschema import Graph
model = json.load(open("haystack-export.json"))
g = Graph(load_brick=True).from_haystack("http://project-haystack.org/carytown#", model)
points = g.query("""SELECT ?point ?type WHERE {
    ?point rdf:type/rdfs:subClassOf* brick:Point .
    ?point rdf:type ?type
}""")
print(points)

VBIS Translation

brickschema can add VBIS tags to a Brick model easily

from brickschema import Graph
g = Graph(load_brick=True)
g.load_file("mybuilding.ttl")
g.expand(profile="vbis")

vbis_tags = g.query("""SELECT ?equip ?vbistag WHERE {
    ?equip  <https://brickschema.org/schema/1.1/Brick/alignments/vbis#hasVBISTag> ?vbistag
}""")

Web-based Interaction

brickschema now supports interacting with a Graph object in a web browser. Executing g.serve(<http address>) on a graph object from your Python script or interpreter will start a webserver listening (by default) at http://localhost:8080 . This uses Yasgui to provide a simple web interface supporting SPARQL queries and inference.

Brick model validation

The module utilizes the pySHACL package to validate a building ontology against the Brick Schema, its default constraints (shapes) and user provided shapes.

from brickschema import Graph

g = Graph(load_brick=True)
g.load_file('myBuilding.ttl')
valid, _, _ = g.validate()
print(f"Graph is valid? {valid}")

# validating using externally-defined shapes
external = Graph()
external.load_file("other_shapes.ttl")
valid, _, _ = g.validate(shape_graphs=[external])
print(f"Graph is valid? {valid}")

The module provides a command brick_validate similar to the pyshacl command. The following command is functionally equivalent to the code above. bash brick_validate myBuilding.ttl -s other_shapes.ttl

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