Part 8: Applying Changes to Ontologies


Apply changes is an experimental feature. This documentation is provided for alpha testers to try out existing functionality. Currently on a fraction of the KGCL specification is implemented.

OAK allows various kinds of changes to be applied to ontologies, including:

  • Changing Names of concepts

  • Adding or removing edges

  • Obsoleting concepts

Like most aspects of OAK, all changes in OAK conform to a Datamodel. The datamodel used by OAK is KGCL.

About KGCL

KGCL is a datamodel for describing changes to ontologies at a high level.

The KGCL datamodel can be expressed in different forms:

  • Natively, as YAML or JSON documents

  • As RDF

  • As Python Objects

  • Using a Domain Specific Language (DSL) optimised for easy reading and writing

OAK uses KGCL objects to communicate desired changes to an ontology. This is an example of the Command Pattern.

For example, rather than simply calling a method obsolete_class(term: CURIE), we instead:

  1. Create a ClassObsoletion object

  2. Pass that object to an implementation of the PatcherInterface

While this involves an additional step, this pattern offers a number of advantages

  • proposed changes can be created in queue and deployed at the appropriate time in the future

  • a single extensible interface can be used, and new operations can be created without changing the interface

Command Line

A subset of commands mutate the ontology specified via the --input option. This includes

  • set-obsolete

  • migrate-curies

With a mutation command, there are a number of different options for how changes are persisted:

  • write in place, using the general option --autosave

  • saving to a new resource using the general option --save-to

  • exporting to a different kind of resource or format using a command-specific --output

The behavior of these options may vary depending on the input, and some may be inapplicable.

For example, if the input is an external triplestore such as Ontobee or Ubergraph, or an external read-only API like BioPortal or OLS then saving in place is not allowed.

Example: Sqlite3

We assume here that we have a local sqlite3 file called go-edit.db and we want to obsolete a concept “nucleus”.

To do this in place:

runoak --autosave -i sqlite:go-edit.db set-obsolete nucleus

This will apply the obsoletion changes directly and update the input file

To instead save to a different sqlite file:

runoak --save-to sqlite:go-edit-out.db -i sqlite:go-edit.db set-obsolete nucleus

Note that exports are not currently implemented for sqlite

Example: OBO Files

To make edits and export to a new file:

runoak  -i go-edit.obo set-obsolete nucleus -o go-edit-out.obo -O obo

This will apply the obsoletion changes in memory and then save results to a separate obo file.