featureselectionoperator.html
来自「数据挖掘方面最新软件」· HTML 代码 · 共 700 行 · 第 1/4 页
HTML
700 行
<!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 1.5.0_13) on Mon Jul 14 01:36:22 CEST 2008 --><TITLE>FeatureSelectionOperator (RapidMiner Class Documentation)</TITLE><META NAME="keywords" CONTENT="com.rapidminer.operator.features.selection.FeatureSelectionOperator class"><LINK REL ="stylesheet" TYPE="text/css" HREF="../../../../../stylesheet.css" TITLE="Style"><SCRIPT type="text/javascript">function windowTitle(){ parent.document.title="FeatureSelectionOperator (RapidMiner Class Documentation)";}</SCRIPT><NOSCRIPT></NOSCRIPT></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=2 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="class-use/FeatureSelectionOperator.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </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="../../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</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="../../../../../com/rapidminer/operator/features/selection/CutSelection.html" title="class in com.rapidminer.operator.features.selection"><B>PREV CLASS</B></A> <A HREF="../../../../../com/rapidminer/operator/features/selection/ForwardSelection.html" title="class in com.rapidminer.operator.features.selection"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../../../index.html?com/rapidminer/operator/features/selection/FeatureSelectionOperator.html" target="_top"><B>FRAMES</B></A> <A HREF="FeatureSelectionOperator.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 | <A HREF="#field_summary">FIELD</A> | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: <A HREF="#field_detail">FIELD</A> | <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">com.rapidminer.operator.features.selection</FONT><BR>Class FeatureSelectionOperator</H2><PRE>java.lang.Object <IMG SRC="../../../../../resources/inherit.gif" ALT="extended by "><A HREF="../../../../../com/rapidminer/operator/Operator.html" title="class in com.rapidminer.operator">com.rapidminer.operator.Operator</A> <IMG SRC="../../../../../resources/inherit.gif" ALT="extended by "><A HREF="../../../../../com/rapidminer/operator/OperatorChain.html" title="class in com.rapidminer.operator">com.rapidminer.operator.OperatorChain</A> <IMG SRC="../../../../../resources/inherit.gif" ALT="extended by "><A HREF="../../../../../com/rapidminer/operator/features/FeatureOperator.html" title="class in com.rapidminer.operator.features">com.rapidminer.operator.features.FeatureOperator</A> <IMG SRC="../../../../../resources/inherit.gif" ALT="extended by "><B>com.rapidminer.operator.features.selection.FeatureSelectionOperator</B></PRE><DL><DT><B>All Implemented Interfaces:</B> <DD><A HREF="../../../../../com/rapidminer/gui/wizards/ConfigurationListener.html" title="interface in com.rapidminer.gui.wizards">ConfigurationListener</A>, <A HREF="../../../../../com/rapidminer/gui/wizards/PreviewListener.html" title="interface in com.rapidminer.gui.wizards">PreviewListener</A>, <A HREF="../../../../../com/rapidminer/parameter/ParameterHandler.html" title="interface in com.rapidminer.parameter">ParameterHandler</A>, <A HREF="../../../../../com/rapidminer/tools/LoggingHandler.html" title="interface in com.rapidminer.tools">LoggingHandler</A></DD></DL><DL><DT><B>Direct Known Subclasses:</B> <DD><A HREF="../../../../../com/rapidminer/operator/features/construction/GeneratingForwardSelection.html" title="class in com.rapidminer.operator.features.construction">GeneratingForwardSelection</A></DD></DL><HR><DL><DT><PRE>public class <B>FeatureSelectionOperator</B><DT>extends <A HREF="../../../../../com/rapidminer/operator/features/FeatureOperator.html" title="class in com.rapidminer.operator.features">FeatureOperator</A></DL></PRE><P><p> This operator realizes the two deterministic greedy feature selection algorithms forward selection and backward elimination. However, we added some enhancements to the standard algorithms which are described below: </p> <h4>Forward Selection</h4> <ol> <li>Create an initial population with <i>n</i> individuals where <i>n</i> is the input example set's number of attributes. Each individual will use exactly one of the features.</li> <li>Evaluate the attribute sets and select only the best <i>k</i>.</li> <li>For each of the <i>k</i> attribute sets do: If there are <i>j</i> unused attributes, make <i>j</i> copies of the attribute set and add exactly one of the previously unused attributes to the attribute set.</li> <li>As long as the performance improved in the last <i>p</i> iterations go to 2</li> </ol> <h4>Backward Elimination</h4> <ol> <li>Start with an attribute set which uses all features.</li> <li>Evaluate all attribute sets and select the best <i>k</i>.</li> <li>For each of the <i>k</i> attribute sets do: If there are <i>j</i> attributes used, make <i>j</i> copies of the attribute set and remove exactly one of the previously used attributes from the attribute set.</li> <li>As long as the performance improved in the last <i>p</i> iterations go to 2</li> </ol> <p> The parameter <i>k</i> can be specified by the parameter <code>keep_best</code>, the parameter <i>p</i> can be specified by the parameter <code>generations_without_improval</code>. These parameters have default values 1 which means that the standard selection algorithms are used. Using other values increase the runtime but might help to avoid local extrema in the search for the global optimum. </p> <p> Another unusual parameter is <code>maximum_number_of_generations</code>. This parameter bounds the number of iterations to this maximum of feature selections / deselections. In combination with <code>generations_without_improval</code> this allows several different selection schemes (which are described for forward selection, backward elimination works analogous): <ul> <li><code>maximum_number_of_generations</code> = <i>m</i> and <code>generations_without_improval</code> = <i>p</i>: Selects maximal <i>m</i> features. The selection stops if not performance improvement was measured in the last <i>p</i> generations.</li> <li><code>maximum_number_of_generations</code> = <i>-1</i> and <code>generations_without_improval</code> = <i>p</i>: Tries to selects new features until no performance improvement was measured in the last <i>p</i> generations.</li> <li><code>maximum_number_of_generations</code> = <i>m</i> and <code>generations_without_improval</code> = <i>-1</i>: Selects maximal <i>m</i> features. The selection stops is not stopped until all combinations with maximal <i>m</i> were tried. However, the result might contain less features than these.</li> <li><code>maximum_number_of_generations</code> = <i>-1</i> and <code>generations_without_improval</code> = <i>-1</i>: Test all combinations of attributes (brute force, this might take a very long time and⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?