C# OpenNLP Name Finder Training

[Andrew Bagshaw <ab...@hotmail.ca>]

Hi! I’m new to OpenNLP and have been playing around with it in C# .NET following the instructions at https://cwiki.apache.org/confluence/display/OPENNLP/Introduction+to+using+openNLP+in+.NET+Projects.


So far everything has been going without a hitch, except I can’t figure out how to use the training API in C# to train a Name Finder model. I’ve been tinkering around without success and can’t seem to find any documentation on this.


I've finally managed to get some code that at least compiles but it gives me this error on the third last line:

An unhandled exception of type 'java.lang.IllegalStateException' occurred in opennlp.dll

Additional information: java.security.NoSuchAlgorithmException: class configured for MessageDigest(provider: SUN)cannot be found.


My code:


FileReader fileReader = new FileReader("train.txt");

 ObjectStream fileStream = new PlainTextByLineStream(fileReader);

 ObjectStream sampleStream = new NameSampleDataStream(fileStream);

 TokenNameFinderModel test;

 test = NameFinderME.train("en", "person", sampleStream, Collections.emptyMap());

 opennlp.tools.namefind.TokenNameFinderModel model = NameFinderME.train("en", "person", sampleStream, Collections.emptyMap()); //I get the error here

 BufferedOutputStream modelOut = new BufferedOutputStream(new FileOutputStream("test.bin"));

model.serialize(modelOut);


I’m not sure if I’m even on the right track with this code. If someone would be kind enough to set me on the right track I would be very grateful.


I have been using the name finder algorithm with the person name finder model with success, although I find that it misses a bunch of names that I would like it to detect. Is there a way that I can add to the model (train it without overwriting the current information in it)? That is what I am trying to accomplish.

Also, if there are any other name finder models you know of (other than the ones supplied on the OpenNLP website) that may be more comprehensive, please let me know. I have hunted around without much success.


Thanks!


Andrew

Re: C# OpenNLP Name Finder Training

[Ram <in...@hotmail.com>]

Hi,

  I faced the same problem and the solution was to copy all IKVM dlls into 
the project (debug/release) folder.  More info can be found at 
http://stackoverflow.com/a/37267275/5575487.

Regards,
Ram

Re: C# OpenNLP Name Finder Training

[Jörn Kottmann <ko...@gmail.com>]

On 01/10/2014 05:30 AM, Andrew Bagshaw wrote:
> Hi! I’m new to OpenNLP and have been playing around with it in C# .NET following the instructions at https://cwiki.apache.org/confluence/display/OPENNLP/Introduction+to+using+openNLP+in+.NET+Projects.
>
>
> So far everything has been going without a hitch, except I can’t figure out how to use the training API in C# to train a Name Finder model. I’ve been tinkering around without success and can’t seem to find any documentation on this.
>
>
> I've finally managed to get some code that at least compiles but it gives me this error on the third last line:
>
> An unhandled exception of type 'java.lang.IllegalStateException' occurred in opennlp.dll
>
> Additional information: java.security.NoSuchAlgorithmException: class configured for MessageDigest(provider: SUN)cannot be found.
>


During the training a hash of all the events is computed with the Java 
API. It looks like that retrieving the MessageDigest fails on .Net.
I am not sure how that can be fixed. Maybe we could use a different 
approach to compute the hash.

A pragmatic solution could be just to epxport the training data to a 
file and afterwards use the command line util to do the training (using 
the JVM).

> My code:
>
>
> FileReader fileReader = new FileReader("train.txt");
>
>   ObjectStream fileStream = new PlainTextByLineStream(fileReader);
>
>   ObjectStream sampleStream = new NameSampleDataStream(fileStream);
>
>   TokenNameFinderModel test;
>
>   test = NameFinderME.train("en", "person", sampleStream, Collections.emptyMap());
>
>   opennlp.tools.namefind.TokenNameFinderModel model = NameFinderME.train("en", "person", sampleStream, Collections.emptyMap()); //I get the error here
>
>   BufferedOutputStream modelOut = new BufferedOutputStream(new FileOutputStream("test.bin"));
>
> model.serialize(modelOut);
>
>
> I’m not sure if I’m even on the right track with this code. If someone would be kind enough to set me on the right track I would be very grateful.


The code looks good.


>
> I have been using the name finder algorithm with the person name finder model with success, although I find that it misses a bunch of names that I would like it to detect. Is there a way that I can add to the model (train it without overwriting the current information in it)? That is what I am trying to accomplish.

No in our current implementation, that is not possible.

To get a well performing NER model you usually need to annotate your own 
data. If you want to process English text, it might be worth to train on 
OntoNotes, OpenNLP
has built-in support for it.

HTH,
Jörn