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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc (build 1.4.2_05) on Mon Mar 07 15:27:46 NZDT 2005 --><TITLE>Instance</TITLE><META NAME="keywords" CONTENT="weka.core.Instance class"><LINK REL ="stylesheet" TYPE="text/css" HREF="../../stylesheet.css" TITLE="Style"><SCRIPT type="text/javascript">function windowTitle(){ parent.document.title="Instance";}</SCRIPT></HEAD><BODY BGCOLOR="white" onload="windowTitle();"><!-- ========= START OF TOP NAVBAR ======= --><A NAME="navbar_top"><!-- --></A><A HREF="#skip-navbar_top" title="Skip navigation links"></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""><TR><TD COLSPAN=3 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../Tutorial.pdf"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="http://www.cs.waikato.ac.nz/ml/weka/index.html"><FONT CLASS="NavBarFont1"><B>Weka's home</B></FONT></A> </TD> </TR></TABLE></TD><TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../weka/core/FastVector.FastVectorEnumeration.html" title="class in weka.core"><B>PREV CLASS</B></A> <A HREF="../../weka/core/Instances.html" title="class in weka.core"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../index.html" target="_top"><B>FRAMES</B></A> <A HREF="Instance.html" target="_top"><B>NO FRAMES</B></A> <SCRIPT type="text/javascript"> <!-- if(window==top) { document.writeln('<A HREF="../../allclasses-noframe.html"><B>All Classes</B></A>'); } //--></SCRIPT><NOSCRIPT> <A HREF="../../allclasses-noframe.html"><B>All Classes</B></A></NOSCRIPT></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: NESTED | FIELD | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: FIELD | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD></TR></TABLE><A NAME="skip-navbar_top"></A><!-- ========= END OF TOP NAVBAR ========= --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">weka.core</FONT><BR>Class Instance</H2><PRE>java.lang.Object <IMG SRC="../../resources/inherit.gif" ALT="extended by"><B>weka.core.Instance</B></PRE><DL><DT><B>All Implemented Interfaces:</B> <DD><A HREF="../../weka/core/Copyable.html" title="interface in weka.core">Copyable</A>, java.io.Serializable</DD></DL><DL><DT><B>Direct Known Subclasses:</B> <DD><A HREF="../../weka/associations/tertius/IndividualInstance.html" title="class in weka.associations.tertius">IndividualInstance</A>, <A HREF="../../weka/core/SparseInstance.html" title="class in weka.core">SparseInstance</A></DD></DL><HR><DL><DT>public class <B>Instance</B><DT>extends java.lang.Object<DT>implements <A HREF="../../weka/core/Copyable.html" title="interface in weka.core">Copyable</A>, java.io.Serializable</DL><P>Class for handling an instance. All values (numeric, nominal, or string) are internally stored as floating-point numbers. If an attribute is nominal (or a string), the stored value is the index of the corresponding nominal (or string) value in the attribute's definition. We have chosen this approach in favor of a more elegant object-oriented approach because it is much faster. <p> Typical usage (code from the main() method of this class): <p> <code> ... <br> // Create empty instance with three attribute values <br> Instance inst = new Instance(3); <br><br> // Set instance's values for the attributes "length", "weight", and "position"<br> inst.setValue(length, 5.3); <br> inst.setValue(weight, 300); <br> inst.setValue(position, "first"); <br><br> // Set instance's dataset to be the dataset "race" <br> inst.setDataset(race); <br><br> // Print the instance <br> System.out.println("The instance: " + inst); <br> ... <br> </code><p> All methods that change an instance are safe, ie. a change of an instance does not affect any other instances. All methods that change an instance's attribute values clone the attribute value vector before it is changed. If your application heavily modifies instance values, it may be faster to create a new instance from scratch.<P><P><DL><DT><B>Version:</B></DT> <DD>$Revision: 1.19.2.1 $</DD><DT><B>Author:</B></DT> <DD>Eibe Frank (eibe@cs.waikato.ac.nz)</DD><DT><B>See Also:</B><DD><A HREF="../../serialized-form.html#weka.core.Instance">Serialized Form</A></DL><HR><P><!-- ======== NESTED CLASS SUMMARY ======== --><!-- =========== FIELD SUMMARY =========== --><!-- ======== CONSTRUCTOR SUMMARY ======== --><A NAME="constructor_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Constructor Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../../weka/core/Instance.html#Instance(double, double[])">Instance</A></B>(double weight, double[] attValues)</CODE><BR> Constructor that inititalizes instance variable with given values.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../../weka/core/Instance.html#Instance(int)">Instance</A></B>(int numAttributes)</CODE><BR> Constructor of an instance that sets weight to one, all values to be missing, and the reference to the dataset to null.</TD></TR></TABLE> <!-- ========== METHOD SUMMARY =========== --><A NAME="method_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Method Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../weka/core/Attribute.html" title="class in weka.core">Attribute</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#attribute(int)">attribute</A></B>(int index)</CODE><BR> Returns the attribute with the given index.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../weka/core/Attribute.html" title="class in weka.core">Attribute</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#attributeSparse(int)">attributeSparse</A></B>(int indexOfIndex)</CODE><BR> Returns the attribute with the given index.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../weka/core/Attribute.html" title="class in weka.core">Attribute</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#classAttribute()">classAttribute</A></B>()</CODE><BR> Returns class attribute.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> int</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#classIndex()">classIndex</A></B>()</CODE><BR> Returns the class attribute's index.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#classIsMissing()">classIsMissing</A></B>()</CODE><BR> Tests if an instance's class is missing.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> double</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#classValue()">classValue</A></B>()</CODE><BR> Returns an instance's class value in internal format.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> java.lang.Object</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#copy()">copy</A></B>()</CODE><BR> Produces a shallow copy of this instance.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../weka/core/Instances.html" title="class in weka.core">Instances</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#dataset()">dataset</A></B>()</CODE><BR> Returns the dataset this instance has access to.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#deleteAttributeAt(int)">deleteAttributeAt</A></B>(int position)</CODE><BR> Deletes an attribute at the given position (0 to numAttributes() - 1).</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> java.util.Enumeration</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#enumerateAttributes()">enumerateAttributes</A></B>()</CODE><BR> Returns an enumeration of all the attributes.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#equalHeaders(weka.core.Instance)">equalHeaders</A></B>(<A HREF="../../weka/core/Instance.html" title="class in weka.core">Instance</A> inst)</CODE><BR> Tests if the headers of two instances are equivalent.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#hasMissingValue()">hasMissingValue</A></B>()</CODE><BR> Tests whether an instance has a missing value.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> int</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#index(int)">index</A></B>(int position)</CODE><BR> Returns the index of the attribute stored at the given position.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#insertAttributeAt(int)">insertAttributeAt</A></B>(int position)</CODE><BR> Inserts an attribute at the given position (0 to numAttributes()).</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#isMissing(weka.core.Attribute)">isMissing</A></B>(<A HREF="../../weka/core/Attribute.html" title="class in weka.core">Attribute</A> att)</CODE><BR> Tests if a specific value is "missing".</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#isMissing(int)">isMissing</A></B>(int attIndex)</CODE><BR> Tests if a specific value is "missing".</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#isMissingSparse(int)">isMissingSparse</A></B>(int indexOfIndex)</CODE><BR> Tests if a specific value is "missing".</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#isMissingValue(double)">isMissingValue</A></B>(double val)</CODE><BR> Tests if the given value codes "missing".</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static void</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#main(java.lang.String[])">main</A></B>(java.lang.String[] options)</CODE><BR> Main method for testing this class.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../weka/core/Instance.html" title="class in weka.core">Instance</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#mergeInstance(weka.core.Instance)">mergeInstance</A></B>(<A HREF="../../weka/core/Instance.html" title="class in weka.core">Instance</A> inst)</CODE><BR> Merges this instance with the given instance and returns the result.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static double</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#missingValue()">missingValue</A></B>()</CODE><BR> Returns the double that codes "missing".</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> int</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#numAttributes()">numAttributes</A></B>()</CODE><BR> Returns the number of attributes.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> int</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#numClasses()">numClasses</A></B>()</CODE><BR> Returns the number of class labels.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> int</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#numValues()">numValues</A></B>()</CODE><BR> Returns the number of values present.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#replaceMissingValues(double[])">replaceMissingValues</A></B>(double[] array)</CODE><BR> Replaces all missing values in the instance with the values contained in the given array.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#setClassMissing()">setClassMissing</A></B>()</CODE><BR> Sets the class value of an instance to be "missing".</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#setClassValue(double)">setClassValue</A></B>(double value)</CODE><BR> Sets the class value of an instance to the given value (internal floating-point format).</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../weka/core/Instance.html#setClassValue(java.lang.String)">setClassValue</A></B>(java.lang.String value)</CODE>⌨️ 快捷键说明
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