Adding database drivers to use WEKA classes

问题:

I tried to run the following command on the command-line:

G:\Weka-3-6>java weka.core.converters.CSVLoader data.csv > data.arff

This is the error message:

---Registering Weka Editors---
Trying to add database driver (JDBC): RmiJdbc.RJDriver - Error, not in CLASSPATH?
Trying to add database driver (JDBC): jdbc.idbDriver - Error, not in CLASSPATH?
Trying to add database driver (JDBC): org.gjt.mm.mysql.Driver - Error, not in CLASSPATH?
Trying to add database driver (JDBC): com.mckoi.JDBCDriver - Error, not in CLASSPATH?
Trying to add database driver (JDBC): org.hsqldb.jdbcDriver - Error, not in CLASSPATH?
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Hashtable.<init>(Unknown Source)
    at java.util.Hashtable.<init>(Unknown Source)
    at java.util.Properties.propertyNames(Unknown Source)
    at weka.core.ProtectedProperties.<init>(ProtectedProperties.java:55)
    at weka.core.Attribute.<init>(Attribute.java:215)
    at weka.core.converters.CSVLoader.readHeader(CSVLoader.java:744)
    at weka.core.converters.CSVLoader.readStructure(CSVLoader.java:416)
    at weka.core.converters.CSVLoader.getStructure(CSVLoader.java:401)
    at weka.core.converters.CSVLoader.getDataSet(CSVLoader.java:434)
    at weka.core.converters.AbstractFileLoader.runFileLoader(AbstractFileLoader.java:323)
    at weka.core.converters.CSVLoader.main(CSVLoader.java:804)

I do see that it speaks something about adding the database drivers to the classpath. What are the steps in adding the database drivers to the classpath? Also, would I need additional software packages?

回答1:

Hi there are are a couple of points there The initial JDBC errors are because weka cannot find the database drivers.

Trying to add database driver (JDBC): RmiJdbc.RJDriver - Error, not in CLASSPATH?
Trying to add database driver (JDBC): jdbc.idbDriver - Error, not in CLASSPATH?
Trying to add database driver (JDBC): org.gjt.mm.mysql.Driver - Error, not in CLASSPATH?
Trying to add database driver (JDBC): com.mckoi.JDBCDriver - Error, not in CLASSPATH?
Trying to add database driver (JDBC): org.hsqldb.jdbcDriver - Error, not in CLASSPATH?

This isn't a major issue as you are loading from CSV but if you want to configure the database connectivity properly then look at http://weka.wikispaces.com/How+do+I+connect+to+a+database%3F

The second issue

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space

is due to the CSV you are trying to load being to large for the default java heap. I don't know how large your data file is but i run weka with about 2gb on my machine with the -Xmx argument you could try.

java -Xmx2200M java weka.core.converters.CSVLoader data.csv > data.arff

where 2200M is the amount of memory you wish to allocate.