Re: [Classifier4j-devel] Training and Classifying

[Nick L. <ni...@ma...>]

Neil Gandhi wrote:

>Hi Nick,
>
>Thanks for the reply, however there is still a problem.
>
>The following outlines how I am trying to access the data I have trained
>in the "word_probability" table.  I wish to classify the String
>'contents' against the data in the "word_probability" table:
>
>	DriverMangerJDBCConnectionManager cm = new
>DriverMangerJDBCConnectionManager(connString, user, pw);
>
>	JDBCWordsDataSource wds = new JDBCWordsDataSource(cm);
>	
>	ITokenizer tokenizer = new DefaultTokenizer();
>
>	IClassifier classifier = new BayesianClassifier(wds, tokenizer);
>
>	classifier.classify(contents);
>
>
>I get a system error message saying:
>net.sf.classifier4J.bayesian.WordsDataSourceException: Problem creating
>table
>
>and
>
>Caused by: java.sql.SQLException: ERROR:  Relation 'word_probability'
>already exists
>
>It seems as if the JDBCWordsDataSource constructor is always trying to
>create a table, when I just want to be able to read from the existing
>table!
>
>I am using a Postgres SQL database.
>
>I would very much appreciate you providing some code which enables me to
>read from the "word_probability" table and then use the standard methods
>to classify an unknown string.
>
>  
>

The code you have is exactly correct.

As previously noted, Classifier4J has been tested with MySQL & HSQLDB. 
PostgreSQL _should_ work fine with it, provided the JDBC driver supports 
the database metadata functionality correctly.

Is PostgreSQL case sensitive with respect to table names? If so there 
was a bug we fixed after the 0.5 release that may effect you. Get the 
latest version from CVS, (or do the change yourself: see 
<http://cvs.sourceforge.net/viewcvs.py/classifier4j/Classifier4J/src/java/net/sf/classifier4J/bayesian/JDBCWordsDataSource.java?r1=1.13&r2=1.14>)

If that doesn't help, can please send the result set returned from the 
following code:

DatabaseMetaData dbm = con.getMetaData();
ResultSet rs = dbm.getTables(null, null, "word_probability", null);

Nick