pyfst: OpenFst in Python

pyfst provides a Python interface to the excellent OpenFst library. Most of the essential functionality of the library is exposed through a simplified API, allowing quick prototyping of algorithms using finite-state methods and easy visual debugging of the results obtained by applying FST operations.

For example, one might write the following code to produce the pyfst logo:

import fst

# Create a first linear chain for 'py', and take its Kleen closure
a = fst.linear_chain(('py',)).closure()

# Create a second acceptor for 'fst'
b = fst.Acceptor(a.isyms)
b.add_arc(0, 1, 'fst')
b[1].final = True

# Concatenate the two transducers
c = a + b

# Remove ε-transitions and minimize

pyfst focuses on providing an intuitive interface to the OpenFst API and lacks support for advanced functionality such as custom semirings and non-vector FST types. However, most operations are available for standard transducers with log and tropical weights, which should be enough for the majority of basic use cases.

pyfst wraps the OpenFst library in Python, making its excellent C++ API easily accessible for quick development and prototyping

Useful links