/// <summary>
/// Creates an instance of a random walk process
/// </summary>
/// <param name="network"></param>
/// <param name="walkmode"></param>
public RandomWalk(TemporalNetwork network, RandomWalkMode walkmode)
{
RandomWalkMode = walkmode;
_network = network;
rand = new Random();
_current_visitations = new Dictionary <string, int>();
_last_visits = new Dictionary <string, int>();
// Set visitations to 0
foreach (string v in network.AggregateNetwork.Vertices)
{
_current_visitations[v] = 0;
}
foreach (string v in network.AggregateNetwork.Vertices)
{
_last_visits[v] = -1000;
}
// Reduce first and second-order aggregate network to strongly connected component
_network.AggregateNetwork.ReduceToLargestStronglyConnectedComponent();
_network.SecondOrderAggregateNetwork.ReduceToLargestStronglyConnectedComponent();
// Initialize random walk
CurrentEdge = StringToTuple(_network.SecondOrderAggregateNetwork.RandomNode);
CurrentNode = CurrentEdge.Item2;
_current_visitations[CurrentNode] = 1;
Time = 1;
// Compute stationary distribution
_stationary_dist = ComputeStationaryDist();
InitializeCumulatives();
}
/// <summary>
/// Creates an instance of a random walk process
/// </summary>
/// <param name="network"></param>
/// <param name="walkmode"></param>
public RandomWalk(TemporalNetwork network, RandomWalkMode walkmode)
{
RandomWalkMode = walkmode;
_network = network;
rand = new Random();
_current_visitations = new Dictionary<string, int>();
_last_visits = new Dictionary<string, int>();
// Set visitations to 0
foreach (string v in network.AggregateNetwork.Vertices)
_current_visitations[v] = 0;
foreach (string v in network.AggregateNetwork.Vertices)
_last_visits[v] = -1000;
// Reduce first and second-order aggregate network to strongly connected component
_network.AggregateNetwork.ReduceToLargestStronglyConnectedComponent();
_network.SecondOrderAggregateNetwork.ReduceToLargestStronglyConnectedComponent();
// Initialize random walk
CurrentEdge = StringToTuple(_network.SecondOrderAggregateNetwork.RandomNode);
CurrentNode = CurrentEdge.Item2;
_current_visitations[CurrentNode] = 1;
Time = 1;
// Compute stationary distribution
_stationary_dist = ComputeStationaryDist();
InitializeCumulatives();
}
/// <summary>
/// Runs a random walk process on an aggregate networks and outputs the dynamics of the infection size
/// </summary>
/// <param name="args"></param>
public static void Run(string[] args)
{
if (args.Length < 3)
{
Console.WriteLine("Usage: TempNet rw [network_file] [output_file] [RWMode=static_first] [aggregationWindow=1] [steps=1000]");
Console.WriteLine("\t where RWMode can be ... ");
Console.WriteLine("\t static_first\t Performs a random walk on the aggregate network that considers betweenness preferences computed from the temporal network");
Console.WriteLine("\t static_second\t ...");
return;
}
string out_file = args[2];
RandomWalkMode mode = RandomWalkMode.StaticFirstOrder;
int runs = 1;
int length = 1000;
int aggregationWindow = 1;
if (args.Length >= 4)
{
if (args[3] == "static_second")
{
mode = RandomWalkMode.StaticSecondOrder;
}
else
{
Console.WriteLine("Unknown walk mode '{0}'", args[3]);
}
}
if (args.Length >= 5)
{
aggregationWindow = int.Parse(args[4]);
}
if (args.Length >= 6)
{
runs = int.Parse(args[5]);
}
if (args.Length >= 7)
{
length = int.Parse(args[6]);
}
if (!CmdlTools.PromptExistingFile(out_file))
{
Console.WriteLine("User opted to exit.");
return;
}
Console.Write("Reading temporal network as undirected network...");
TemporalNetwork temp_net = TemporalNetwork.ReadFromFile(args[1], true);
Console.WriteLine("done.");
if (aggregationWindow != 1)
{
Console.WriteLine("Applying aggregation window, length = {0}, time steps before = {1}", aggregationWindow, temp_net.Length);
temp_net.AggregateTime(aggregationWindow);
Console.WriteLine("done, time steps after = {0}", temp_net.Length);
}
Console.Write("Building aggregate network...");
WeightedNetwork aggregateNet = temp_net.AggregateNetwork;
Console.WriteLine("done.");
Console.WriteLine("Starting random walk ...");
Dictionary <int, double> tvd = new Dictionary <int, double>();
RandomWalk walk = new RandomWalk(temp_net, mode);
for (int t = 0; t < length; t++)
{
walk.Step();
tvd[t] = walk.TVD;
Console.WriteLine("Node = {0}, step = {1}, tvd={2:0.000}", walk.CurrentNode, t, tvd[t]);
}
Console.Write("Writing time series of total variation distance ...");
StringBuilder sb = new StringBuilder();
foreach (var step in tvd)
{
sb.AppendLine(string.Format(System.Globalization.CultureInfo.GetCultureInfo("en-US").NumberFormat, "{0} {1}", step.Key, step.Value));
}
System.IO.File.WriteAllText(out_file + ".dat", sb.ToString());
Console.WriteLine(" done.");
}
