distancefunction.html

weka是机器学习和数据挖掘领域最有影响力的开源项目之一

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<B>Method Detail</B></FONT></TH>
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<A NAME="setInstances(weka.core.Instances)"><!-- --></A><H3>
setInstances</H3>
<PRE>
void <B>setInstances</B>(<A HREF="../../weka/core/Instances.html" title="class in weka.core">Instances</A>&nbsp;insts)</PRE>
<DL>
<DD>Sets the instances
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</DD>
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<A NAME="getInstances()"><!-- --></A><H3>
getInstances</H3>
<PRE>
<A HREF="../../weka/core/Instances.html" title="class in weka.core">Instances</A> <B>getInstances</B>()</PRE>
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<DD>returns the instances currently set
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</DL>
</DD>
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</DD>
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<A NAME="distance(weka.core.Instance, weka.core.Instance)"><!-- --></A><H3>
distance</H3>
<PRE>
double <B>distance</B>(<A HREF="../../weka/core/Instance.html" title="class in weka.core">Instance</A>&nbsp;first,
                <A HREF="../../weka/core/Instance.html" title="class in weka.core">Instance</A>&nbsp;second)
                throws java.lang.Exception</PRE>
<DL>
<DD>Calculates the distance between two instances.
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<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>first</CODE> - the first instance<DD><CODE>second</CODE> - the second instance
<DT><B>Returns:</B><DD>the distance between the two given instances,
<DT><B>Throws:</B>
<DD><CODE>java.lang.Exception</CODE></DL>
</DD>
</DL>
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<A NAME="distance(weka.core.Instance, weka.core.Instance, double)"><!-- --></A><H3>
distance</H3>
<PRE>
double <B>distance</B>(<A HREF="../../weka/core/Instance.html" title="class in weka.core">Instance</A>&nbsp;first,
                <A HREF="../../weka/core/Instance.html" title="class in weka.core">Instance</A>&nbsp;second,
                double&nbsp;cutOffValue)
                throws java.lang.Exception</PRE>
<DL>
<DD>Calculates the distance between two instances. Offers speed up (if the 
 distance function class in use supports it) in nearest neighbour search by 
 taking into account the cutOff or maximum distance. Depending on the 
 distance function class, post processing of the distances by 
 postProcessDistances(double []) may be required if this function is used.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>first</CODE> - the first instance<DD><CODE>second</CODE> - the second instance<DD><CODE>cutOffValue</CODE> - If the distance being calculated becomes larger than 
                    cutOffValue then the rest of the calculation is 
                    discarded.
<DT><B>Returns:</B><DD>the distance between the two given instances or Double.MAX_VALUE
 if the distance being calculated becomes larger than cutOffValue.
<DT><B>Throws:</B>
<DD><CODE>java.lang.Exception</CODE></DL>
</DD>
</DL>
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<A NAME="postProcessDistances(double[])"><!-- --></A><H3>
postProcessDistances</H3>
<PRE>
void <B>postProcessDistances</B>(double[]&nbsp;distances)</PRE>
<DL>
<DD>Does post processing of the distances (if necessary) returned by
 distance(distance(Instance first, Instance second, double cutOffValue). It
 may be necessary, depending on the distance function, to do post processing
 to set the distances on the correct scale. Some distance function classes
 may not return correct distances using the cutOffValue distance function to 
 minimize the inaccuracies resulting from floating point comparison and 
 manipulation.
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<DD><DL>
</DL>
</DD>
<DD><DL>
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<A NAME="update(weka.core.Instance)"><!-- --></A><H3>
update</H3>
<PRE>
void <B>update</B>(<A HREF="../../weka/core/Instance.html" title="class in weka.core">Instance</A>&nbsp;ins)
            throws java.lang.Exception</PRE>
<DL>
<DD>Update the distance function (if necessary) for the newly added instance.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Throws:</B>
<DD><CODE>java.lang.Exception</CODE></DL>
</DD>
</DL>
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