+++ /dev/null
-/*
- * Copyright (c) 2003-2005 The BISON Project
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- *
- */
-
-package peersim.util;
-
-/**
-* A class that can keep track of some statistics like variance, average, min,
-* max incrementally. That is, when adding a new data item, it updates the
-* statistics.
-*/
-public class IncrementalStats {
-
-
-// ===================== fields ========================================
-// =====================================================================
-
-
-private double min;
-
-private double max;
-
-private double sum;
-
-private double sqrsum;
-
-private int n;
-
-private int countmin;
-
-private int countmax;
-
-// ====================== initialization ==============================
-// ====================================================================
-
-
-/** Calls {@link #reset}. */
-public IncrementalStats() { reset(); }
-
-// --------------------------------------------------------------------
-
-/** Resets the statistics to reflect the zero elements set.
-* Min and max are set to positive and negative infinity, respectively.
-*/
-public void reset() {
-
- countmin=0;
- countmax=0;
- min = Double.POSITIVE_INFINITY;
- max = Double.NEGATIVE_INFINITY;
- sum = 0.0;
- sqrsum = 0.0;
- n = 0;
-}
-
-
-// ======================== methods ===================================
-// ====================================================================
-
-
-/** Updates the statistics according to this element. It calls
-* <code>add(item,1)</code>.
-* @see #add(double,int) */
-public final void add( double item ) { add(item,1); }
-
-// --------------------------------------------------------------------
-
-/** Updates the statistics assuming element <code>item</code> is added
-* <code>k</code> times.*/
-public void add( double item, int k ) {
-
- if( item < min )
- {
- min = item;
- countmin = 0;
- }
- if( item == min ) countmin+=k;
- if( item > max )
- {
- max = item;
- countmax = 0;
- }
- if(item == max) countmax+=k;
- n+=k;
- if( k == 1 )
- {
- sum += item;
- sqrsum += item*item;
- }
- else
- {
- sum += item*k;
- sqrsum += item*item*k;
- }
-}
-
-// --------------------------------------------------------------------
-
-/** The number of data items processed so far */
-public int getN() { return n; }
-
-// --------------------------------------------------------------------
-
-/** The maximum of the data items */
-public double getMax() { return max; }
-
-// --------------------------------------------------------------------
-
-/** The minimum of the data items */
-public double getMin() { return min; }
-
-// --------------------------------------------------------------------
-
-/** Returns the number of data items whose value equals the maximum. */
-public int getMaxCount() { return countmax; }
-
-// --------------------------------------------------------------------
-
-/** Returns the number of data items whose value equals the minimum. */
-public int getMinCount() { return countmin; }
-
-// --------------------------------------------------------------------
-
-/** The sum of the data items */
-public double getSum() { return sum; }
-
-// --------------------------------------------------------------------
-
-/** The sum of the squares of the data items */
-public double getSqrSum() { return sqrsum; }
-
-// --------------------------------------------------------------------
-
-/** The average of the data items */
-public double getAverage() { return sum/n; }
-
-// --------------------------------------------------------------------
-
-/** The empirical variance of the data items. Guaranteed to be larger or
-equal to 0.0. If due to rounding errors the value becomes negative,
-it returns 0.0.*/
-public double getVar() {
-
- double var=
- (((double)n) / (n-1)) * (sqrsum/n - getAverage()*getAverage());
- return (var>=0.0?var:0.0);
- // XXX note that we have very little possibility to increase numeric
- // stability if this class is "greedy", ie, if it has no memory
- // In a more precise implementation we could delay the calculation of
- // statistics and store the data in some intelligent structure
-}
-
-// --------------------------------------------------------------------
-
-/** the empirical standard deviation of the data items */
-public double getStD() { return Math.sqrt(getVar()); }
-
-// --------------------------------------------------------------------
-
-/**
-* Prints the following quantities separated by spaces in a single line
-* in this order.
-* Minimum, maximum, number of items, average, variance, number of minimal
-* items, number of maximal items.
-*/
-public String toString() {
-
- return min+" "+max+" "+n+" "+sum/n+" "+getVar()+" "+
- countmin+" "+countmax;
-}
-
-}
-
