Malt Parser throwing class not found exception

Question

I'm trying to parse sentence with Malt Parser in NLTK. When I did raw_parse(sent) it gave an error with exit code 1. I executed java command on terminal and it gives class Not Found exception, I don't understand what is wrong now?

java -Xmx1024m -jar /usr/local/bin/malt.jar -w /home/abc/maltparser-1.7.2 -c engmalt.linear-1.7 -i /home/abc/maltparser-1.7.2/malt_input.conllrPZgwc -o /home/abc/maltparser-1.7.2/malt_output.conllDMSKpg -m parse Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Layout

Note that the latest version of NLTK has this module patched up nicely, see stackoverflow.com/questions/33015326/… — alvas

danger89 danger89 · Accepted Answer · 2014-02-09T16:32:10

Your working directory is not correctly set. Log4j is a package used by Malt Parser (see: maltparser-1.7.2/lib/log4j.jar). Which is used for logging logically.

In order to run maltparser in NLTK, the working directory should be set to this folder (in your case: /home/abc/maltparser-1.7.2).

So, step one is getting the latest NLTK from git:

git clone https://github.com/nltk/nltk.git

Install NLTK:

sudo python setup.py install

To run Malt Parser using NLTK try this code example:

import os
import nltk

os.environ['MALTPARSERHOME']="/home/abc/maltparser-1.7.2"
verbose = False
maltParser = nltk.parse.malt.MaltParser(working_dir="/home/abc/maltparser-1.7.2", 
    mco="engmalt.linear-1.7",
    additional_java_args=['-Xmx512m'])
print(maltParser.raw_parse('This is a test sentence', verbose=verbose).tree().pprint())

As you may notice I'm using the pre-learned mco file (engmalt.linear-1.7), which can be downloaded from here: http://www.maltparser.org/mco/english_parser/engmalt.html

Move this mco file to: /home/abc/maltparser-1.7.2 directory.

Finally NLTK only except malt.jar. So create a copy (or rename):

cp maltparser-1.7.2.jar malt.jar

Which can still be located in your /home/abc/maltparser-1.7.2.jar directory.

Hopefully you'll get it running!

Malt Parser throwing class not found exception

1 Answers