Frog for Python

This is a Python binding to the Natural Language Processing suite Frog. Frog is intended for Dutch and performs part-of-speech tagging, lemmatisation, morphological analysis, named entity recognition, shallow parsing, and dependency parsing. The tool itself is implemented in C++ (https://languagemachines.github.io/frog). The binding requires Python 3.6 or higher.

Installation

Linux

On modern Linux distributions, we recommend you use a Python virtual environment and install using pip:

pip install python-frog

When possible on your system (glibc >= 2.28, x86_64), this will install the binary Python wheels that include Frog and all necessary dependencies except for frogdata. To download and install the data (in ~/.config/frog) you then only need to run the following once:

python -c "import frog; frog.installdata()"

If you want language detection support, ensure you the have libexttextcat package (if provided by your distribution) installed prior to executing the above command.

If the binary wheels are not available for your distribution, you will need to first install Frog yourself.

Alpine Linux

First install Cython and Frog (apk add cython frog frog-dev), then pip install python-frog (preferably in a Python virtual environment)

Arch Linux

You can alternatively use the AUR package .

macOS

First use homebrew to install Frog:

brew tap fbkarsdorp/homebrew-lamachine
brew install frog

Then install this binding using pip (preferably in a Python virtual environment):

pip install python-frog

Windows

Not supported natively, but you should be able to use the Frog python binding if you use WSL.

Usage

Example:

import frog

frog = frog.Frog(frog.FrogOptions(parser=False))
output = frog.process_raw("Dit is een test")
print("RAW OUTPUT=",output)
output = frog.process("Dit is nog een test.")
print("PARSED OUTPUT=",output)

Output:

RAW OUTPUT= 1   Dit     dit     [dit]   VNW(aanw,pron,stan,vol,3o,ev)
0.777085        O       B-NP
2       is      zijn    [zijn]  WW(pv,tgw,ev)   0.999891        O
B-VP
3       een     een     [een]   LID(onbep,stan,agr)     0.999113        O
B-NP
4       test    test    [test]  N(soort,ev,basis,zijd,stan)     0.789112
O       I-NP


PARSED OUTPUT= [{'chunker': 'B-NP', 'index': '1', 'lemma': 'dit', 'ner':
'O', 'pos': 'VNW(aanw,pron,stan,vol,3o,ev)', 'posprob': 0.777085, 'text':
'Dit', 'morph': '[dit]'}, {'chunker': 'B-VP', 'index': '2', 'lemma':
'zijn', 'ner': 'O', 'pos': 'WW(pv,tgw,ev)', 'posprob': 0.999966, 'text':
'is', 'morph': '[zijn]'}, {'chunker': 'B-NP', 'index': '3', 'lemma': 'nog',
'ner': 'O', 'pos': 'BW()', 'posprob': 0.99982, 'text': 'nog', 'morph':
'[nog]'}, {'chunker': 'I-NP', 'index': '4', 'lemma': 'een', 'ner': 'O',
'pos': 'LID(onbep,stan,agr)', 'posprob': 0.995781, 'text': 'een', 'morph':
'[een]'}, {'chunker': 'I-NP', 'index': '5', 'lemma': 'test', 'ner': 'O',
'pos': 'N(soort,ev,basis,zijd,stan)', 'posprob': 0.903055, 'text': 'test',
'morph': '[test]'}, {'chunker': 'O', 'index': '6', 'eos': True, 'lemma':
'.', 'ner': 'O', 'pos': 'LET()', 'posprob': 1.0, 'text': '.', 'morph':
'[.]'}]

Available keyword arguments for FrogOptions:

• tok - True/False - Do tokenisation? (default: True)
• lemma - True/False - Do lemmatisation? (default: True)
• morph - True/False - Do morpholigical analysis? (default: True)
• daringmorph - True/False - Do morphological analysis in new experimental style? (default: False)
• mwu - True/False - Do Multi Word Unit detection? (default: True)
• chunking - True/False - Do Chunking/Shallow parsing? (default: True)
• ner - True/False - Do Named Entity Recognition? (default: True)
• parser - True/False - Do Dependency Parsing? (default: False).
• xmlin - True/False - Input is FoLiA XML (default: False)
• xmlout - True/False - Output is FoLiA XML (default: False)
• docid - str - Document ID (for FoLiA)
• numThreads - int - Number of threads to use (default: unset, unlimited)

You can specify a Frog configuration file explicitly as second argument upon instantiation, otherwise the default one is used:

frog = frog.Frog(frog.FrogOptions(parser=False), "/path/to/your/frog.cfg")

A third parameter, a dictionary, can be used to override specific configuration values (same syntax as Frog's --override option), you may want to leave the second parameter empty if you want to load the default configuration:

frog = frog.Frog(frog.FrogOptions(parser=False), "", { "tokenizer.rulesFile": "tokconfig-nld-twitter" })

FoLiA support

Frog supports output in the FoLiA XML format (set FrogOptions(xmlout=True)), as well as FoLiA input (set FrogOptions(xmlin=True)). The FoLiA format exposes more details about the linguistic annotation in a more structured and more formal way.

Whenever FoLiA output is requested, the process() method will return an instance of folia.Document, which is provided by the FoLiApy library. This loads the entire FoLiA document in memory and allows you to inspect it in any way you see fit. Extensive documentation for this library can be found here: http://folia.readthedocs.io/

An example can be found below:

from frog import Frog, FrogOptions

frog = Frog(FrogOptions(parser=True,xmlout=True))
output = frog.process("Dit is een FoLiA test.")
#output is now no longer a string but an instance of folia.Document, provided by the FoLiA library in PyNLPl (pynlpl.formats.folia)
print("FOLIA OUTPUT AS RAW XML=")
print(output.xmlstring())

print("Inspecting FoLiA output (just a small example):")
for word in output.words():
    print(word.text() + " " + word.pos() + " " + word.lemma())