fst_runtime 0.2.1

A runtime environment for querying FSTs stored in the AT&T `.att` format.

fst-runtime

The fst_runtime python package is written as a light-weight front-end for finite-state transducers compiled to AT&T's .att format via programs like foma, hfst, etc. This runtime reads the FST into memory from the .att file, and publishes two main query functions, down_generation and up_analysis, that walk the FST either down (wal+VERB+GER -> walking) or up (walking -> wal+VERB+GER), respectively.

There are also methods for bulk querying, down_generations and up_analyses.

Documentation for this project can be found at https://culturefoundryca.github.io/fst-runtime/.

Installation Instructions

This package is published on PyPI and can be installed via pip install fst_runtime or poetry add fst_runtime, etc.

Weighted FSTs

This runtime supports weighted FSTs, where the weights are defined under a semiring. Common semirings are provided via fst_runtime.semiring.

Example Usage

from fst_runtime.fst import Fst

fst = Fst('/home/username/fsts/walk.att')

generations = fst.down_generation('wal', suffixes=[['+VERB'], ['+GER', '+INF']])

for generation in generations:
    print(generation)

This example, based off of tests/data/fst4.att, would then return the results of wal+VERB+GER and wal+VERB+INF which would be ['walking', 'walk']. If you simply called fst.down_generation('wal'), it would generate all possible wordforms of it in the FST.

Similarly with up:

analyses = fst.up_analysis('walking')

for analysis in analyses:
    print(analysis)

In this case, we only get one result back, wal+VERB+GER.

Acknowledgements

We would like to thank Dr. Miikka Silfverberg for his help in deciding what this application should look like, and for providing test FSTs for us to use to test the application.

We would also like to thank UBC's ELF-Lab for the use of the waabam walk through their fully-fledged Ojibwe FST. You can find their repo here: https://github.com/ELF-Lab/OjibweMorph.

Also thank you to Sandra Radic for some early application code.

Development

For working on this project, please consult the wiki for the project's architecture and dev setup. PRs welcome.