This a presentation about how to use and install the KafNafParserPy library, which could be used to read and modify KAF or NAF files

1. KafNafParserPy
A python library for parsing KAF/NAF
Ruben Izquierdo Bevia
Vrije University of Amsterdam
CLTL meeting 19th Nov 2014

2. What is KAF / NAF ?
• Annotations formats to represent linguistic information
o XML based
o Different information in different layers interconnected
o Easy to be used in NLP pipelines
• KAF
o https://github.com/opener-project/kaf/wiki/KAF-structure-overview
• NAF
o http://www.newsreader-project.eu/files/2013/01/techreport.pdf

3. What is the
KafNafParserPy
• It is a Python module/library
• It allows to parse a KAF or NAF file
o Read all the layers
o Provides access to the information by means of python classes (methods and
attributes)
• It allows to generate new KAF/NAF files
o Create new layers
o Modify existing ones
• It allows to convert NAF  KAF

4. KafNafParserPy
philosophy
• No validation against DTD (just valid as XML)
• Python object for each XML element (header, text,
token,terms…)
• The attributes are not “parsed/read”
o The KAF/NAF attributes are not defined as attributes for a class
o Just the pointer to the XML element is stored
• It provides access to all the attributes on “real time”
• Modifications are made “on the fly”
o If you change the object in memory  you will need to dump it to a new
file to keep the results

5. KafNafParserPy
philosophy
• Class Cterm (encapsulate a KAF/NAF term)
o Attributes:
• string lemma
• string pos
• string morphofeat
• Cspan span ….
o Methods
• get_lemma(…)  returns the lemma attribute
• get_pos(…)  returns the pos attribute
• …..

6. KafNafParserPy
philosophy
• Class Cterm (encapsulate a KAF/NAF term)
o Attributes:
• string lemma
• string pos
• string morphofeat
• Cspan span ….
o Methods
• get_lemma(…)  returns the lemma attribute
• get_pos(…)  returns the pos attribute
• …..

7. KafNafParserPy
philosophy
• Class Cterm (encapsulate a KAF/NAF term)
o Attributes:
• string type (is NAF or KAF?)
• Pointer to the xml element
o Methods
• get_lemma(…)  returns xml_element.get(‘lemma’)
• get_pos(…)  returns xml_element.get(‘pos’)
• get_id(…)
o xml_element.get(‘id’) for NAF
o xml_element.get(‘tid’) for KAF

8. Getting Started I
• https://github.com/cltl/KafNafParserPy
• Basic steps:
o Install lxml library for Python
• pip install lxml
o Clone the repository
• git clone https://github.com/cltl/KafNafParserPy
o Make it available for Python
• Put it on the same folder of the scripts that will import
• Add it to PYTHON_PATH
• Create a symbolic link in your virtualenv
• …

9. Getting Started II
• Documentation:
o HTML: http://kyoto.let.vu.nl/~izquierdo/api/KafNafParserPy/
o PDF: http://kyoto.let.vu.nl/~izquierdo/api/KafNafParserPy/api.pdf
• Entry point always
o Module KafNafParserPy
o Class KafNafParser

10. Getting tokens
• How could I?
o We just have a “KafNafParser” object
• Go to the API and check the methods for the
KafNafParser class

11. Getting tokens
• How could I?
o We just have a “KafNafParser” object
• Go to the API and check the methods for the
KafNafParser class

12. Getting tokens
• How could I?
o We just have a “KafNafParser” object
• Go to the API and check the methods for the
KafNafParser class

13. Getting tokens

14. Getting terms
• Use KafNafParser::get_terms(…)
• Use methods of Cterm

15. Modifying one token
• Change w7->War to Battle

16. Modifying one token
• Object “my_parser” after set_text(…)
o is updated with “Battle” in memory
o Original file “entities_example.naf” is not changed
• If we want to keep the changes
o Close the program  clean memory  changes lost
o We will need to dump the object to a new file
• Could be a (string) filename or an open file

17. Read entities
• KafNafParser::get_entities() is an iterator for
entities
• Centity::get_external_references() is an iterator for
external references

18. Adding a new external
reference
1. Create the new object external reference
o “from KafNafParserPy import KafNafParser”
o “from KafNafParserPy import *”
2. Set the attributes with the set_XYZ() methods
1. Add the new object to the layer/tree
o By adding it to the specific element (the entity if we have it)
o By adding it to the general parser object providing the identifier (sometimes not
implemented)

19. Adding a new external
reference
• Create the new external reference
• Find the element where we want to add it
• Use the “adding” method of the element

20. Adding a new external
reference
• Create the new external reference
• Use the “adding” method of the parser and
providing the id
• Not always implemented (quite easy to do)

21. KafNafParserPy
Ruben Izquierdo Bevia
ruben.izquierdobevia@vu.nl
http://rubenizquierdobevia.com
 GitHub
https://github.com/cltl/KafNafParserPy
 API html
http://kyoto.let.vu.nl/~izquierdo/api/KafNafParserPy/
 API pdf
http://kyoto.let.vu.nl/~izquierdo/api/KafNafParserPy/api.pdf