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ixa-pipe-chunk is a chunker currently offering pre-trained models for English. ixa-pipe-chunk is part of IXA pipes, a multilingual set of 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-chunk. 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.


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


ixa-pipe-chunk provides Perceptron models (Collins 2002) for chunking. To avoid duplication of efforts, we use and contribute to the machine learning API provided by the Apache OpenNLP project.

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


  • Latest model: chunk-models-1.1.0.

  • English Chunk Models:

    • CoNLL 2000 data: en-perceptron-conll00.bin: 92.96


ixa-pipe-chunk provides 4 basic functionalities:

  1. tag: reads a NAF document containing wf elements and creates term elements with the morphological information.
  2. train: trains new models for with several options available (read file for details).
  3. eval: evaluates a trained model with a given test set.
  4. cross: perform cross-validation evaluation.
  5. server: server mode.
  6. client: client mode.

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

java -jar target/ixa-pipe-chunk-$version-exec.jar (tag|train|eval|cross) -help


If you are in hurry, just execute:

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

If you want to know more, please follow reading.

ixa-pipe-chunk reads NAF documents containing wf 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-pos by piping it with ixa-pipe-tok and ixa-pipe-pos

There are several options to tag with ixa-pipe-chunk:

  • model: it is required to provide the model to do the tagging.
  • lang: choose between en and eu. If no language is chosen, the one specified in the NAF header will be used.

Tagging Example:

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


To train a new model, you just need to pass a training parameters file as an argument. Every training option is documented in the template file.


java -jar target/ixa.pipe.chunk-$version-exec.jar train -p


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

  • model: input the name of the model to evaluate.
  • testSet: testset to evaluate the model.
  • evalReport: choose the detail in displaying the results:
    • brief: it just prints the word accuracy.
    • detailed: detailed report with confusion matrixes and so on.
    • error: print to stderr all the false positives.


java -jar target/ixa.pipe.chunk-$version-exec.jar eval -m test-chunk.bin -l en -t


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



The javadoc of the module is located here:


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
+      A template properties file containing documention
+ Furthermore, the installation process, as described in the, will generate another directory:
target/                 it contains binary executable and other directories


Installing the ixa-pipe-chunk 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/java8
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/java8
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. Download the models

Download the models:

tar xvzf chunk-models.tar.gz

5. Compile

cd ixa-pipe-chunk
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 or newer 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