Package weka.filters
Class SimpleStreamFilter
- java.lang.Object
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- weka.filters.Filter
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- weka.filters.SimpleFilter
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- weka.filters.SimpleStreamFilter
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- All Implemented Interfaces:
java.io.Serializable
,CapabilitiesHandler
,OptionHandler
,RevisionHandler
,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
.
The following code snippet uses the filterSomeFilter
on a dataset that is loaded fromfilename
.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()
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: 9718 $
- Author:
- FracPete (fracpete at waikato dot ac dot nz)
- See Also:
SimpleBatchFilter
,input(Instance)
,batchFinished()
,Filter.m_FirstBatchDone
, Serialized Form
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Constructor Summary
Constructors Constructor Description SimpleStreamFilter()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description 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.SimpleFilter
debugTipText, getDebug, getOptions, globalInfo, listOptions, setDebug, setInputFormat, setOptions
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Methods inherited from class weka.filters.Filter
batchFilterFile, filterFile, getCapabilities, getCapabilities, getOutputFormat, getRevision, isFirstBatchDone, isNewBatch, isOutputFormatDefined, main, makeCopies, makeCopy, numPendingOutput, output, outputPeek, toString, useFilter, wekaStaticWrapper
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Method Detail
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input
public boolean input(Instance instance) throws java.lang.Exception
Input an instance for filtering. Filter requires all training instances be read before producing output.
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batchFinished
public boolean batchFinished() throws java.lang.Exception
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 classFilter
- Returns:
- true if there are instances pending output
- Throws:
java.lang.IllegalStateException
- if no input format has been set.java.lang.NullPointerException
- if no input structure has been defined,java.lang.Exception
- if there was a problem finishing the batch.
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