I don't see any correlation between index and degree with the attached
test code (which rejects duplicate connections because it uses HashSet).
Cheers,
Michael
Matthew Toseland wrote:
Hmmm, we really need to fix this, if our simulations are skewed...
Any hints, Oskar? The network construction function is right at the top of
this file.. could you have a look at it? Thanks.
http://emu.freenetproject.org/cgi-bin/viewcvs.cgi/trunk/freenet/src/freenet/node/simulator/RealNodeTest.java?rev=18322&view=markup
On Monday 03 March 2008 21:40, [EMAIL PROTECTED] wrote:
Author: robert
Date: 2008-03-03 21:40:44 +0000 (Mon, 03 Mar 2008)
New Revision: 18322
Modified:
trunk/freenet/src/freenet/node/simulator/RealNodeTest.java
Log:
comments
Modified: trunk/freenet/src/freenet/node/simulator/RealNodeTest.java
===================================================================
--- trunk/freenet/src/freenet/node/simulator/RealNodeTest.java 2008-03-03
13:38:58 UTC (rev 18321)
+++ trunk/freenet/src/freenet/node/simulator/RealNodeTest.java 2008-03-03
21:40:44 UTC (rev 18322)
@@ -29,6 +29,10 @@
/*
Borrowed from mrogers simulation code (February 6, 2008)
+ --
+ FIXME: May not generate good networks. Presumably this is because the
arrays are always scanned
+ [0..n], some nodes tend to have *much* higher connections than the
degree (the first few),
+ starving the latter ones.
*/
static void makeKleinbergNetwork (Node[] nodes, boolean idealLocations,
int degree, boolean forceNeighbourConnections)
{
------------------------------------------------------------------------
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import java.util.ArrayList;
import java.util.HashSet;
class KleinbergDegreeTest
{
static final int NODES = 1000, DEGREE = 10, MAX_DEGREE = 20;
static final boolean LIMIT = false;
ArrayList<Node> nodes;
KleinbergDegreeTest()
{
nodes = new ArrayList<Node> (NODES);
for (int i = 0; i < NODES; i++) nodes.add (new Node());
}
void makeKleinbergNetwork()
{
for (Node a : nodes) {
// Normalise the probabilities
double norm = 0.0;
for (Node b : nodes) {
if (a.location == b.location) continue;
norm += 1.0 / distance (a, b);
}
// Create DEGREE/2 outgoing connections
for (Node b : nodes) {
if (a.location == b.location) continue;
double p = 1.0 / distance (a, b) / norm;
for (int i = 0; i < DEGREE / 2; i++) {
if (Math.random() < p) {
connect (a, b);
break;
}
}
}
}
}
double distance (Node a, Node b)
{
double x = a.location, y = b.location;
if (x > y) return Math.min (x - y, y - x + 1.0);
else return Math.min (y - x, x - y + 1.0);
}
void connect (Node a, Node b)
{
if (LIMIT &&
(a.neighbours.size() == MAX_DEGREE
|| b.neighbours.size() == MAX_DEGREE)) return;
a.neighbours.add (b);
b.neighbours.add (a);
}
// Print a scatterplot of index vs degree and a histogram of degree
void printDegreeDistribution()
{
int[] histogram = new int[DEGREE];
for (int i = 0; i < NODES; i++) {
Node n = nodes.get (i);
System.out.println (i + " " + n.neighbours.size());
int degree = n.neighbours.size();
if (degree >= histogram.length) {
int[] newHistogram = new int[degree + 1];
for (int j = 0; j < histogram.length; j++)
newHistogram[j] = histogram[j];
histogram = newHistogram;
}
histogram[degree]++;
}
System.out.print ("#");
for (int i = 0; i < histogram.length; i++)
System.out.print (" " + histogram[i]);
System.out.println();
}
public static void main (String[] args)
{
KleinbergDegreeTest kdt = new KleinbergDegreeTest();
kdt.makeKleinbergNetwork();
kdt.printDegreeDistribution();
}
class Node
{
HashSet<Node> neighbours = new HashSet<Node>();
double location = Math.random();
}
}
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