Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time


Build Status GitHub license

ixa-pipe-parse is a statistical constituent parser for English and Spanish. ixa-pipe-parse is part of IXA pipes, a set of multilingual NLP tools developed by the IXA NLP Group []. Current version is 1.1.1.

Please go to [] for general information about the IXA pipes tools but also for official releases, including source code and binary packages for all the tools in the IXA pipes toolkit.

This document is intended to be the usage guide of ixa-pipe-parse. If you really need to clone and install this repository instead of using the releases provided in [], please scroll down to the end of the document for the installation instructions.

NOTICE!!: ixa-pipe-parse is now in Maven Central for easy access to its API.


  1. Overview of ixa-pipe-parse
  2. Usage of ixa-pipe-parse
  1. API via Maven Dependency
  2. Git installation


ixa-pipe-parse provides:

  • Constituent parsing for English trained on the Penn Treebank and for Spanish trained on the Ancora corpus.
  • HeadFinders based on Collins head rules (Michael Collins PhD thesis, 1999).

For this first release we provide two Maximum Entropy models based on a bottom-up shift-reduce method as described by Adwait Ratnaparkhi (1999). To avoid duplication of efforts, we use the machine learning API provided by the Apache OpenNLP project to train and deploy the models.

Therefore, the following models are provided in the parse-models.tgz package:

  • English Models:
    • Penn Treebank: en-parser-chunking.bin: F1 87.42
  • Spanish Models:
    • CoNLL es-parser-chunking.bin: F1 88.40

ixa-pipe-parse is distributed under Apache License version 2.0 (see LICENSE.txt for details).


ixa-pipe-parse provides 3 basic functionalities:

  1. parse: reads a NAF document containing wf and term elements and provides the parsing trees.
  2. train: trains new model for English or Spanish with several options available (not yet available).
  3. eval: functionalities to help evaluating a given model with a given test set.

Each of these functionalities are accessible by adding (parse|train|eval) as a subcommand to ixa-pipe-parse-$version.jar. Please read below and check the -help parameter:

java -jar target/ixa-pipe-parse-$version.jar (parse|train|eval) -help


If you are in hurry, just execute:

cat file.txt | ixa-pipe-tok | ixa-pipe-pos | java -jar $PATH/target/ixa-pipe-parse-$version.jar parse -m model.bin

If you want to know more, please follow reading.

ixa-pipe-parse reads NAF documents (with wf and term elements) via standard input and outputs NAF through standard output. The NAF format specification is here:


You can get the necessary input for ixa-pipe-parse by piping ixa-pipe-tok and ixa-pipe-pos as shown in the example.

There are several options to parse with ixa-pipe-parse:

  • language: choose between en and es. If no language is chosen, the one specified in the NAF header will be used.
  • model: provide the model to do the parsing.
  • outputFormat: oneline EVALB format or NAF (the default).
  • headFinder: mark constituent headwords using the rules (and variants of) defined in Collins's thesis (1999).


cat file.txt | ixa-pipe-tok | ixa-pipe-pos | java -jar $PATH/target/ixa-pipe-parse-$version.jar parse -m model.bin

Training new models

This option is in progress, not yet available.


To evaluate a trained model, the eval subcommand provides the following options:

  • language: input en or es.
  • model: input the name of the model to evaluate.
  • test: reads a tokenized gold standard and produces the test parse for evaluation with EVALB.
  • headFinder: mark constituent headwords based on Collins's thesis (1999).
  • addHeads: reads directory/file containing oneline treebank format trees and annotate the headwords.


java -jar target/ixa.pipe.parse-$version.jar eval --test gold.tok -l en --model test.bin --nokaf > reference.tree


The easiest way to use ixa-pipe-tok programatically is via Apache Maven. Add this dependency to your pom.xml:



It is possible to generate the javadoc of the module by executing:

cd ixa-pipe-parse/
mvn javadoc:jar

Which will create a jar file core/target/ixa-pipe-parse-$version-javadoc.jar

Module contents

The contents of the module are the following:

+ formatter.xml           Apache OpenNLP code formatter for Eclipse SDK
+ pom.xml                 maven pom file which deals with everything related to compilation and execution of the module
+ src/                    java source code of the module and required resources
+ Furthermore, the installation process, as described in the, will generate another directory:
target/                 it contains binary executable and other directories


Installing the ixa-pipe-parse requires the following steps:

If you already have installed in your machine the Java 1.7+ and MAVEN 3, please go to step 3 directly. Otherwise, follow these steps:

1. Install JDK 1.7 or JDK 1.8

If you do not install JDK 1.7 in a default location, you will probably need to configure the PATH in .bashrc or .bash_profile:

export JAVA_HOME=/yourpath/local/java7
export PATH=${JAVA_HOME}/bin:${PATH}

If you use tcsh you will need to specify it in your .login as follows:

setenv JAVA_HOME /usr/java/java17
setenv PATH ${JAVA_HOME}/bin:${PATH}

If you re-login into your shell and run the command

java -version

You should now see that your JDK is 1.7

2. Install MAVEN 3

Download MAVEN 3 from


Now you need to configure the PATH. For Bash Shell:

export MAVEN_HOME=/home/ragerri/local/apache-maven-3.0.5
export PATH=${MAVEN_HOME}/bin:${PATH}

For tcsh shell:

setenv MAVEN3_HOME ~/local/apache-maven-3.0.5
setenv PATH ${MAVEN3}/bin:{PATH}

If you re-login into your shell and run the command

mvn -version

You should see reference to the MAVEN version you have just installed plus the JDK 7 that is using.

3. Get module source code

If you must get the module source code from here do this:

git clone

4. Dowload the Models

Download and untar the models:

tar xvzf parse-models.tgz

5. Compile

cd ixa-pipe-parse
mvn clean package

This step will create a directory called target/ which contains various directories and files. Most importantly, there you will find the module executable:


This executable contains every dependency the module needs, so it is completely portable as long as you have a JVM 1.7 installed.

To install the module in the local maven repository, usually located in ~/.m2/, execute:

mvn clean install

Contact information

Rodrigo Agerri
University of the Basque Country (UPV/EHU)
E-20018 Donostia-San Sebastián