utils.html

< 数据挖掘--实用机器学习技术及java实现> 一书结合数据挖掘和机器学习的知识,作者陈述了自动挖掘模式的基础理论,并且以java语言实现了具有代表性的各类数据挖掘方法.例如:class

</DL>
<HR>

<A NAME="sm(double, double)"><!-- --></A><H3>
sm</H3>
<PRE>
public static boolean <B>sm</B>(double&nbsp;a,
                         double&nbsp;b)</PRE>
<DL>
<DD>Tests if a is smaller than b.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>a</CODE> - a double<DD><CODE>b</CODE> - a double</DL>
</DD>
</DL>
<HR>

<A NAME="gr(double, double)"><!-- --></A><H3>
gr</H3>
<PRE>
public static boolean <B>gr</B>(double&nbsp;a,
                         double&nbsp;b)</PRE>
<DL>
<DD>Tests if a is smaller than b.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>a</CODE> - a double<DD><CODE>b</CODE> - a double</DL>
</DD>
</DL>
<HR>

<A NAME="log2(double)"><!-- --></A><H3>
log2</H3>
<PRE>
public static double <B>log2</B>(double&nbsp;a)</PRE>
<DL>
<DD>Returns the logarithm of a for base 2.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>a</CODE> - a double</DL>
</DD>
</DL>
<HR>

<A NAME="maxIndex(double[])"><!-- --></A><H3>
maxIndex</H3>
<PRE>
public static int <B>maxIndex</B>(double[]&nbsp;doubles)</PRE>
<DL>
<DD>Returns index of maximum element in a given
 array of doubles. First maximum is returned.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>doubles</CODE> - the array of doubles<DT><B>Returns:</B><DD>the index of the maximum element</DL>
</DD>
</DL>
<HR>

<A NAME="maxIndex(int[])"><!-- --></A><H3>
maxIndex</H3>
<PRE>
public static int <B>maxIndex</B>(int[]&nbsp;ints)</PRE>
<DL>
<DD>Returns index of maximum element in a given
 array of integers. First maximum is returned.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>ints</CODE> - the array of integers<DT><B>Returns:</B><DD>the index of the maximum element</DL>
</DD>
</DL>
<HR>

<A NAME="mean(double[])"><!-- --></A><H3>
mean</H3>
<PRE>
public static double <B>mean</B>(double[]&nbsp;vector)</PRE>
<DL>
<DD>Computes the mean for an array of doubles.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>vector</CODE> - the array<DT><B>Returns:</B><DD>the mean</DL>
</DD>
</DL>
<HR>

<A NAME="minIndex(int[])"><!-- --></A><H3>
minIndex</H3>
<PRE>
public static int <B>minIndex</B>(int[]&nbsp;ints)</PRE>
<DL>
<DD>Returns index of minimum element in a given
 array of integers. First minimum is returned.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>ints</CODE> - the array of integers<DT><B>Returns:</B><DD>the index of the minimum element</DL>
</DD>
</DL>
<HR>

<A NAME="minIndex(double[])"><!-- --></A><H3>
minIndex</H3>
<PRE>
public static int <B>minIndex</B>(double[]&nbsp;doubles)</PRE>
<DL>
<DD>Returns index of minimum element in a given
 array of doubles. First minimum is returned.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>doubles</CODE> - the array of doubles<DT><B>Returns:</B><DD>the index of the minimum element</DL>
</DD>
</DL>
<HR>

<A NAME="normalize(double[])"><!-- --></A><H3>
normalize</H3>
<PRE>
public static void <B>normalize</B>(double[]&nbsp;doubles)</PRE>
<DL>
<DD>Normalizes the doubles in the array by their sum.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>doubles</CODE> - the array of double<DT><B>Throws:</B><DD><CODE>java.lang.IllegalArgumentException</CODE> - if sum is Zero or NaN</DL>
</DD>
</DL>
<HR>

<A NAME="normalize(double[], double)"><!-- --></A><H3>
normalize</H3>
<PRE>
public static void <B>normalize</B>(double[]&nbsp;doubles,
                             double&nbsp;sum)</PRE>
<DL>
<DD>Normalizes the doubles in the array using the given value.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>doubles</CODE> - the array of double<DD><CODE>sum</CODE> - the value by which the doubles are to be normalized<DT><B>Throws:</B><DD><CODE>java.lang.IllegalArgumentException</CODE> - if sum is zero or NaN</DL>
</DD>
</DL>
<HR>

<A NAME="round(double)"><!-- --></A><H3>
round</H3>
<PRE>
public static int <B>round</B>(double&nbsp;value)</PRE>
<DL>
<DD>Rounds a double to the next nearest integer value. The JDK version
 of it doesn't work properly.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>value</CODE> - the double value<DT><B>Returns:</B><DD>the resulting integer value</DL>
</DD>
</DL>
<HR>

<A NAME="roundDouble(double, int)"><!-- --></A><H3>
roundDouble</H3>
<PRE>
public static double <B>roundDouble</B>(double&nbsp;value,
                                 int&nbsp;afterDecimalPoint)</PRE>
<DL>
<DD>Rounds a double to the given number of decimal places.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>value</CODE> - the double value<DD><CODE>afterDecimalPoint</CODE> - the number of digits after the decimal point<DT><B>Returns:</B><DD>the double rounded to the given precision</DL>
</DD>
</DL>
<HR>

<A NAME="sort(int[])"><!-- --></A><H3>
sort</H3>
<PRE>
public static int[] <B>sort</B>(int[]&nbsp;array)</PRE>
<DL>
<DD>Sorts a given array of integers in ascending order and returns an 
 array of integers with the positions of the elements of the original 
 array in the sorted array. The sort is stable. (Equal elements remain
 in their original order.)<DD><DL>
<DT><B>Parameters:</B><DD><CODE>array</CODE> - this array is not changed by the method!<DT><B>Returns:</B><DD>an array of integers with the positions in the sorted
 array.</DL>
</DD>
</DL>
<HR>

<A NAME="sort(double[])"><!-- --></A><H3>
sort</H3>
<PRE>
public static int[] <B>sort</B>(double[]&nbsp;array)</PRE>
<DL>
<DD>Sorts a given array of doubles in ascending order and returns an
 array of integers with the positions of the elements of the
 original array in the sorted array. NOTE THESE CHANGES: the sort
 is no longer stable and it doesn't use safe floating-point
 comparisons anymore. Occurrences of Double.NaN are treated as 
 Double.MAX_VALUE<DD><DL>
<DT><B>Parameters:</B><DD><CODE>array</CODE> - this array is not changed by the method!<DT><B>Returns:</B><DD>an array of integers with the positions in the sorted
 array.</DL>
</DD>
</DL>
<HR>

<A NAME="stableSort(double[])"><!-- --></A><H3>
stableSort</H3>
<PRE>
public static int[] <B>stableSort</B>(double[]&nbsp;array)</PRE>
<DL>
<DD>Sorts a given array of doubles in ascending order and returns an 
 array of integers with the positions of the elements of the original 
 array in the sorted array. The sort is stable (Equal elements remain
 in their original order.) Occurrences of Double.NaN are treated as 
 Double.MAX_VALUE<DD><DL>
<DT><B>Parameters:</B><DD><CODE>array</CODE> - this array is not changed by the method!<DT><B>Returns:</B><DD>an array of integers with the positions in the sorted
 array.</DL>
</DD>
</DL>
<HR>

<A NAME="variance(double[])"><!-- --></A><H3>
variance</H3>
<PRE>
public static double <B>variance</B>(double[]&nbsp;vector)</PRE>
<DL>
<DD>Computes the variance for an array of doubles.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>vector</CODE> - the array<DT><B>Returns:</B><DD>the variance</DL>
</DD>
</DL>
<HR>

<A NAME="sum(double[])"><!-- --></A><H3>
sum</H3>
<PRE>
public static double <B>sum</B>(double[]&nbsp;doubles)</PRE>
<DL>
<DD>Computes the sum of the elements of an array of doubles.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>doubles</CODE> - the array of double</DL>
</DD>
</DL>
<HR>

<A NAME="sum(int[])"><!-- --></A><H3>
sum</H3>
<PRE>
public static int <B>sum</B>(int[]&nbsp;ints)</PRE>
<DL>
<DD>Computes the sum of the elements of an array of integers.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>ints</CODE> - the array of integers</DL>
</DD>
</DL>
<HR>

<A NAME="xlogx(int)"><!-- --></A><H3>
xlogx</H3>
<PRE>
public static double <B>xlogx</B>(int&nbsp;c)</PRE>
<DL>
<DD>Returns c*log2(c) for a given integer value c.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>c</CODE> - an integer value</DL>
</DD>
</DL>
<HR>

<A NAME="main(java.lang.String[])"><!-- --></A><H3>
main</H3>
<PRE>
public static void <B>main</B>(java.lang.String[]&nbsp;ops)</PRE>
<DL>
<DD>Main method for testing this class.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>ops</CODE> - some dummy options</DL>
</DD>
</DL>
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