weka.filters
Class SimpleStreamFilter
java.lang.Object
weka.filters.Filter
weka.filters.SimpleFilter
weka.filters.SimpleStreamFilter
- All Implemented Interfaces:
- java.io.Serializable, CapabilitiesHandler, OptionHandler, StreamableFilter
- Direct Known Subclasses:
- ClassAssigner, MultiFilter, NumericCleaner, RandomSubset
public abstract class SimpleStreamFilter
- extends SimpleFilter
- implements StreamableFilter
This filter is a superclass for simple stream filters.
General notes:
- After the first call of batchFinished() the field m_FirstBatchDone is
set to
true
.
Example:
The following code snippet uses the filter SomeFilter
on a
dataset that is loaded from filename
.
import weka.core.*;
import weka.filters.*;
import java.io.*;
...
SomeFilter filter = new SomeFilter();
// set necessary options for the filter
Instances data = new Instances(
new BufferedReader(
new FileReader(filename)));
Instances filteredData = Filter.useFilter(data, filter);
Implementation:
Only the following abstract methods need to be implemented:
- globalInfo()
- determineOutputFormat(Instances)
- process(Instance)
And the getCapabilities() method must return what kind of
attributes and classes the filter can handle.
If more options are necessary, then the following methods need to be
overriden:
- listOptions()
- setOptions(String[])
- getOptions()
To make the filter available from commandline one must add the following
main method for correct execution (<Filtername> must be replaced
with the actual filter classname):
public static void main(String[] args) {
runFilter(new <Filtername>(), args);
}
Example implementation:
import weka.core.*;
import weka.core.Capabilities.*;
import weka.filters.*;
import java.util.Random;
public class SimpleStream
extends SimpleStreamFilter {
public String globalInfo() {
return "A simple stream filter that adds an attribute 'bla' at the end containing a random number.";
}
public Capabilities getCapabilities() {
Capabilities result = super.getCapabilities();
result.enableAllAttributes();
result.enableAllClasses();
result.enable(Capability.NO_CLASS); // filter doesn't need class to be set
return result;
}
protected Instances determineOutputFormat(Instances inputFormat) {
Instances result = new Instances(inputFormat, 0);
result.insertAttributeAt(new Attribute("bla"), result.numAttributes());
return result;
}
protected Instance process(Instance inst) {
double[] values = new double[inst.numAttributes() + 1];
for (int n = 0; n < inst.numAttributes(); n++)
values[n] = inst.value(n);
values[values.length - 1] = new Random().nextInt();
Instance result = new Instance(1, values);
return result;
}
public static void main(String[] args) {
runFilter(new SimpleStream(), args);
}
}
Options:
Valid filter-specific options are:
-D
Turns on output of debugging information.
- Version:
- $Revision: 1.8 $
- Author:
- FracPete (fracpete at waikato dot ac dot nz)
- See Also:
SimpleBatchFilter
,
input(Instance)
,
batchFinished()
,
Filter.m_FirstBatchDone
,
Serialized Form
Method Summary |
boolean |
batchFinished()
Signify that this batch of input to the filter is finished. |
boolean |
input(Instance instance)
Input an instance for filtering. |
Methods inherited from class weka.filters.Filter |
batchFilterFile, filterFile, getCapabilities, getCapabilities, getOutputFormat, isFirstBatchDone, isNewBatch, isOutputFormatDefined, main, makeCopies, makeCopy, numPendingOutput, output, outputPeek, toString, useFilter, wekaStaticWrapper |
Methods inherited from class java.lang.Object |
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait |
SimpleStreamFilter
public SimpleStreamFilter()
input
public boolean input(Instance instance)
- Input an instance for filtering. Filter requires all
training instances be read before producing output.
- Overrides:
input
in class Filter
- Parameters:
instance
- the input instance
- Returns:
- true if the filtered instance may now be
collected with output().
- Throws:
java.lang.IllegalStateException
- if no input structure has been defined
batchFinished
public boolean batchFinished()
- Signify that this batch of input to the filter is finished. If
the filter requires all instances prior to filtering, output()
may now be called to retrieve the filtered instances. Any
subsequent instances filtered should be filtered based on setting
obtained from the first batch (unless the setInputFormat has been
re-assigned or new options have been set).
- Overrides:
batchFinished
in class Filter
- Returns:
- true if there are instances pending output
- Throws:
java.lang.IllegalStateException
- if no input format has been set.