instances.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

<DD><DL>
<DT><B>Parameters:</B><DD><CODE>att</CODE> - the Attribute object<DD><CODE>k</CODE> - the value of k
<DT><B>Returns:</B><DD>the kth-smallest value</DL>
</DD>
</DL>
<HR>

<A NAME="kthSmallestValue(int, int)"><!-- --></A><H3>
kthSmallestValue</H3>
<PRE>
public double <B>kthSmallestValue</B>(int&nbsp;attIndex,
                               int&nbsp;k)</PRE>
<DL>
<DD>Returns the kth-smallest attribute value of a numeric attribute.
 Note that calling this method will change the order of the data!
 The number of non-missing values in the data must be as least
 as last as k for this to work.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>attIndex</CODE> - the attribute's index<DD><CODE>k</CODE> - the value of k
<DT><B>Returns:</B><DD>the kth-smallest value</DL>
</DD>
</DL>
<HR>

<A NAME="lastInstance()"><!-- --></A><H3>
lastInstance</H3>
<PRE>
public <A HREF="../../weka/core/Instance.html" title="class in weka.core">Instance</A> <B>lastInstance</B>()</PRE>
<DL>
<DD>Returns the last instance in the set.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Returns:</B><DD>the last instance in the set</DL>
</DD>
</DL>
<HR>

<A NAME="meanOrMode(int)"><!-- --></A><H3>
meanOrMode</H3>
<PRE>
public double <B>meanOrMode</B>(int&nbsp;attIndex)</PRE>
<DL>
<DD>Returns the mean (mode) for a numeric (nominal) attribute as
 a floating-point value. Returns 0 if the attribute is neither nominal nor 
 numeric. If all values are missing it returns zero.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>attIndex</CODE> - the attribute's index (index starts with 0)
<DT><B>Returns:</B><DD>the mean or the mode</DL>
</DD>
</DL>
<HR>

<A NAME="meanOrMode(weka.core.Attribute)"><!-- --></A><H3>
meanOrMode</H3>
<PRE>
public double <B>meanOrMode</B>(<A HREF="../../weka/core/Attribute.html" title="class in weka.core">Attribute</A>&nbsp;att)</PRE>
<DL>
<DD>Returns the mean (mode) for a numeric (nominal) attribute as a
 floating-point value.  Returns 0 if the attribute is neither
 nominal nor numeric.  If all values are missing it returns zero.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>att</CODE> - the attribute
<DT><B>Returns:</B><DD>the mean or the mode</DL>
</DD>
</DL>
<HR>

<A NAME="numAttributes()"><!-- --></A><H3>
numAttributes</H3>
<PRE>
public int <B>numAttributes</B>()</PRE>
<DL>
<DD>Returns the number of attributes.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Returns:</B><DD>the number of attributes as an integer</DL>
</DD>
</DL>
<HR>

<A NAME="numClasses()"><!-- --></A><H3>
numClasses</H3>
<PRE>
public int <B>numClasses</B>()</PRE>
<DL>
<DD>Returns the number of class labels.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Returns:</B><DD>the number of class labels as an integer if the class 
 attribute is nominal, 1 otherwise.
<DT><B>Throws:</B>
<DD><CODE><A HREF="../../weka/core/UnassignedClassException.html" title="class in weka.core">UnassignedClassException</A></CODE> - if the class is not set</DL>
</DD>
</DL>
<HR>

<A NAME="numDistinctValues(int)"><!-- --></A><H3>
numDistinctValues</H3>
<PRE>
public int <B>numDistinctValues</B>(int&nbsp;attIndex)</PRE>
<DL>
<DD>Returns the number of distinct values of a given attribute.
 Returns the number of instances if the attribute is a
 string attribute. The value 'missing' is not counted.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>attIndex</CODE> - the attribute (index starts with 0)
<DT><B>Returns:</B><DD>the number of distinct values of a given attribute</DL>
</DD>
</DL>
<HR>

<A NAME="numDistinctValues(weka.core.Attribute)"><!-- --></A><H3>
numDistinctValues</H3>
<PRE>
public int <B>numDistinctValues</B>(<A HREF="../../weka/core/Attribute.html" title="class in weka.core">Attribute</A>&nbsp;att)</PRE>
<DL>
<DD>Returns the number of distinct values of a given attribute.
 Returns the number of instances if the attribute is a
 string attribute. The value 'missing' is not counted.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>att</CODE> - the attribute
<DT><B>Returns:</B><DD>the number of distinct values of a given attribute</DL>
</DD>
</DL>
<HR>

<A NAME="numInstances()"><!-- --></A><H3>
numInstances</H3>
<PRE>
public int <B>numInstances</B>()</PRE>
<DL>
<DD>Returns the number of instances in the dataset.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Returns:</B><DD>the number of instances in the dataset as an integer</DL>
</DD>
</DL>
<HR>

<A NAME="randomize(java.util.Random)"><!-- --></A><H3>
randomize</H3>
<PRE>
public void <B>randomize</B>(java.util.Random&nbsp;random)</PRE>
<DL>
<DD>Shuffles the instances in the set so that they are ordered 
 randomly.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>random</CODE> - a random number generator</DL>
</DD>
</DL>
<HR>

<A NAME="readInstance(java.io.Reader)"><!-- --></A><H3>
readInstance</H3>
<PRE>
public boolean <B>readInstance</B>(java.io.Reader&nbsp;reader)
                     throws java.io.IOException</PRE>
<DL>
<DD>Reads a single instance from the reader and appends it
 to the dataset.  Automatically expands the dataset if it
 is not large enough to hold the instance. This method does
 not check for carriage return at the end of the line.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>reader</CODE> - the reader
<DT><B>Returns:</B><DD>false if end of file has been reached
<DT><B>Throws:</B>
<DD><CODE>java.io.IOException</CODE> - if the information is not read 
 successfully</DL>
</DD>
</DL>
<HR>

<A NAME="relationName()"><!-- --></A><H3>
relationName</H3>
<PRE>
public java.lang.String <B>relationName</B>()</PRE>
<DL>
<DD>Returns the relation's name.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>

<DT><B>Returns:</B><DD>the relation's name as a string</DL>
</DD>
</DL>
<HR>

<A NAME="renameAttribute(int, java.lang.String)"><!-- --></A><H3>
renameAttribute</H3>
<PRE>
public void <B>renameAttribute</B>(int&nbsp;att,
                            java.lang.String&nbsp;name)</PRE>
<DL>
<DD>Renames an attribute. This change only affects this
 dataset.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>att</CODE> - the attribute's index (index starts with 0)<DD><CODE>name</CODE> - the new name</DL>
</DD>
</DL>
<HR>

<A NAME="renameAttribute(weka.core.Attribute, java.lang.String)"><!-- --></A><H3>
renameAttribute</H3>
<PRE>
public void <B>renameAttribute</B>(<A HREF="../../weka/core/Attribute.html" title="class in weka.core">Attribute</A>&nbsp;att,
                            java.lang.String&nbsp;name)</PRE>
<DL>
<DD>Renames an attribute. This change only affects this
 dataset.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>att</CODE> - the attribute<DD><CODE>name</CODE> - the new name</DL>
</DD>
</DL>
<HR>

<A NAME="renameAttributeValue(int, int, java.lang.String)"><!-- --></A><H3>
renameAttributeValue</H3>
<PRE>
public void <B>renameAttributeValue</B>(int&nbsp;att,
                                 int&nbsp;val,
                                 java.lang.String&nbsp;name)</PRE>
<DL>
<DD>Renames the value of a nominal (or string) attribute value. This
 change only affects this dataset.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>att</CODE> - the attribute's index (index starts with 0)<DD><CODE>val</CODE> - the value's index (index starts with 0)<DD><CODE>name</CODE> - the new name</DL>
</DD>
</DL>
<HR>

<A NAME="renameAttributeValue(weka.core.Attribute, java.lang.String, java.lang.String)"><!-- --></A><H3>
renameAttributeValue</H3>
<PRE>
public void <B>renameAttributeValue</B>(<A HREF="../../weka/core/Attribute.html" title="class in weka.core">Attribute</A>&nbsp;att,
                                 java.lang.String&nbsp;val,
                                 java.lang.String&nbsp;name)</PRE>
<DL>
<DD>Renames the value of a nominal (or string) attribute value. This
 change only affects this dataset.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>att</CODE> - the attribute<DD><CODE>val</CODE> - the value<DD><CODE>name</CODE> - the new name</DL>
</DD>
</DL>
<HR>

<A NAME="resample(java.util.Random)"><!-- --></A><H3>
resample</H3>
<PRE>
public <A HREF="../../weka/core/Instances.html" title="class in weka.core">Instances</A> <B>resample</B>(java.util.Random&nbsp;random)</PRE>
<DL>
<DD>Creates a new dataset of the same size using random sampling
 with replacement.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>random</CODE> - a random number generator
<DT><B>Returns:</B><DD>the new dataset</DL>
</DD>
</DL>
<HR>

<A NAME="resampleWithWeights(java.util.Random)"><!-- --></A><H3>
resampleWithWeights</H3>
<PRE>
public <A HREF="../../weka/core/Instances.html" title="class in weka.core">Instances</A> <B>resampleWithWeights</B>(java.util.Random&nbsp;random)</PRE>
<DL>
<DD>Creates a new dataset of the same size using random sampling
 with replacement according to the current instance weights. The
 weights of the instances in the new dataset are set to one.
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>random</CODE> - a random number generator
<DT><B>Returns:</B><DD>the new dataset</DL>
</DD>
</DL>
<HR>

<A NAME="resampleWithWeights(java.util.Random, double[])"><!-- --></A><H3>
resampleWithWeights</H3>
<PRE>
public <A HREF="../../weka/core/Instances.html" title="class in weka.core">Instances</A> <B>resampleWithWeights</B>(java.util.Random&nbsp;random,
                                     double[]&nbsp;weights)</PRE>
<DL>
<DD>Creates a new dataset of the same size using random sampling
 with replacement according to the given weight vector. The
 weights of the instances in the new dataset are set to one.
 The length of the weight vector ha