distancefunction.html

数据挖掘的最常用工具。由于开源

<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Returns:</B><DD>the current instances</DL>
</DD>
</DL>
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<A NAME="setAttributeIndices(java.lang.String)"><!-- --></A><H3>
setAttributeIndices</H3>
<PRE>
void <B>setAttributeIndices</B>(java.lang.String&nbsp;value)</PRE>
<DL>
<DD>Sets the range of attributes to use in the calculation of the distance.
 The indices start from 1, 'first' and 'last' are valid as well. 
 E.g.: first-3,5,6-last
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>value</CODE> - the new attribute index range</DL>
</DD>
</DL>
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<A NAME="getAttributeIndices()"><!-- --></A><H3>
getAttributeIndices</H3>
<PRE>
java.lang.String <B>getAttributeIndices</B>()</PRE>
<DL>
<DD>Gets the range of attributes used in the calculation of the distance.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Returns:</B><DD>the attribute index range</DL>
</DD>
</DL>
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<A NAME="setInvertSelection(boolean)"><!-- --></A><H3>
setInvertSelection</H3>
<PRE>
void <B>setInvertSelection</B>(boolean&nbsp;value)</PRE>
<DL>
<DD>Sets whether the matching sense of attribute indices is inverted or not.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>value</CODE> - if true the matching sense is inverted</DL>
</DD>
</DL>
<HR>

<A NAME="getInvertSelection()"><!-- --></A><H3>
getInvertSelection</H3>
<PRE>
boolean <B>getInvertSelection</B>()</PRE>
<DL>
<DD>Gets whether the matching sense of attribute indices is inverted or not.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Returns:</B><DD>true if the matching sense is inverted</DL>
</DD>
</DL>
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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)</PRE>
<DL>
<DD>Calculates the distance between two instances.
<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
<DT><B>Returns:</B><DD>the distance between the two given instances</DL>
</DD>
</DL>
<HR>

<A NAME="distance(weka.core.Instance, weka.core.Instance, weka.core.neighboursearch.PerformanceStats)"><!-- --></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,
                <A HREF="../../weka/core/neighboursearch/PerformanceStats.html" title="class in weka.core.neighboursearch">PerformanceStats</A>&nbsp;stats)
                throws java.lang.Exception</PRE>
<DL>
<DD>Calculates the distance between two instances.
<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>stats</CODE> - the performance stats object
<DT><B>Returns:</B><DD>the distance between the two given instances
<DT><B>Throws:</B>
<DD><CODE>java.lang.Exception</CODE> - if calculation fails</DL>
</DD>
</DL>
<HR>

<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)</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.POSITIVE_INFINITY if the distance being 
                        calculated becomes larger than cutOffValue.</DL>
</DD>
</DL>
<HR>

<A NAME="distance(weka.core.Instance, weka.core.Instance, double, weka.core.neighboursearch.PerformanceStats)"><!-- --></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,
                <A HREF="../../weka/core/neighboursearch/PerformanceStats.html" title="class in weka.core.neighboursearch">PerformanceStats</A>&nbsp;stats)</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.<DD><CODE>stats</CODE> - the performance stats object
<DT><B>Returns:</B><DD>the distance between the two given instances or 
                        Double.POSITIVE_INFINITY if the distance being 
                        calculated becomes larger than cutOffValue.</DL>
</DD>
</DL>
<HR>

<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.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>distances</CODE> - the distances to post-process</DL>
</DD>
</DL>
<HR>

<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)</PRE>
<DL>
<DD>Update the distance function (if necessary) for the newly added instance.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>ins</CODE> - the instance to add</DL>
</DD>
</DL>
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