public void doTask()
{
ModelUndo mu = new ModelUndo(m_agent);
TimeSpan elapsed = DateTime.Now - m_timer;
try
{
do
{
lock (m_stat_mutex)
{
if (m_samples >= m_num_simulations)
{
break;
}
m_samples++;
}
m_agent.spc.gbl_search_root.sample(m_agent, m_rng, 0);
elapsed = DateTime.Now - m_timer;
} while (Math.Abs(elapsed.TotalMilliseconds) < m_time_limit);
}
catch (Exception e)
{
//m_agent.logbox.Items.Add(e.Message);
// m_agent.logbox.Items.Add(e.StackTrace);
// m_agent.logbox.Items.Add(e.InnerException);
}
}
/* selects the best action determined by the MCTS statistics */
public action_t selectBestMCTSAction(Agent agent)
{
ModelUndo mu = new ModelUndo(agent);
action_t best_action = agent.selectRandomAction(agent.rng);
double best_exp = double.NegativeInfinity;
bool found = false;
for (UInt64 a = 0; a < agent.numActions(); a++)
{
SearchNode n = agent.spc.findNode(agent.hashAfterAction(a));
if (n != null)
{
double noise = agent.rng.NextDouble() * 0.0001;
double exp = n.expectation() + noise;
if (exp > best_exp)
{
best_exp = n.expectation();
best_action = a;
found = true;
}
// agent.logbox.Items.Add("action " + a + ":" + exp + " visits " + n.visits() + " self-predicted probability :" + agent.getPredictedActionProb(a));
}
}
//agent.logbox.Items.Add(" selectBestMCTSAction=" + best_action +"found ="+found );
return(best_action);
}
// perform a sample run through this node and it's children,
// returning the accumulated reward from this sample run
public double sample(Agent agent, Random rng, int dfr)
{
// TODO: implement
if (dfr == (int)agent.horizon() * 2)
{
return(0.0);
}
ModelUndo undo = new ModelUndo(agent);
double reward = 0.0;
if (m_chance_node)
{ // handle chance nodes
// generate a hypothetical percept
symbol_list_t percept = new symbol_list_t(0); //(UInt64)(agent.m_obs_bits + agent.m_rew_bits));
agent.genPerceptAndUpdate(rng, percept);
// extract the reward for this transition, and
// update the agent model
reward = agent.rewardFromPercept(percept);
SearchNode n = agent.spc.findOrCreateNode(agent.hash(), false);
reward += n.sample(agent, rng, dfr + 1);
agent.modelRevert(undo);
}
else
{ // handle decision nodes
lock (m_mutex)
{
// if we need to do a playout
bool do_playout =
visits() < MinVisitsBeforeExpansion ||
dfr >= MaxDistanceFromRoot ||
agent.spc.search_node_pool.Count >= (int)agent.spc.MaxSearchNodes;
if (do_playout)
{
//m_mutex.unlock();
reward = playout(agent, rng, (int)agent.horizon() - dfr / 2);
}
else
{
// pick an action
UInt64 a = selectAction(agent, rng);
//m_mutex.unlock();
// update model, and recurse
agent.modelUpdate(a);
SearchNode n = agent.spc.findOrCreateNode(agent.hash(), true);
reward = n.sample(agent, rng, dfr + 1);
agent.modelRevert(undo);
}
}
}
{ // update our statistics for this node
lock (m_mutex)
{
double vc = (double)(m_visits);
m_mean = (m_mean * vc + reward) / (vc + 1.0);
m_visits++;
}
}
return(reward);
}
public action_t naiveMonteCarlo(Agent agent)
{
DateTime ti = DateTime.Now;
TimeSpan elapsed = ti - ti;
// determine the depth and number of seconds to search
double time_limit_ms = double.Parse((string)agent.options["cycle-length-ms"]);
double time_limit = time_limit_ms / 1000.0;
// sufficient statistics to compute the sample mean for each action
// std::vector<std::pair<reward_t, double> > r(agent.numActions());
double [] rfirst = new double [agent.numActions()];
double [] rsecond = new double[agent.numActions()];
for (int i = 0; i < (int)agent.numActions(); i++)
{
rfirst[i] = rsecond[i] = 0.0;
}
ModelUndo mu = new ModelUndo(agent);
UInt64 total_samples = 0;
UInt64 start_hist_len = agent.historySize();
do // we ensure each action always has one estimate
{
for (UInt64 i = 0; i < agent.numActions(); i++)
{
// make action
agent.modelUpdate(i);
// grab percept and determine immediate reward
symbol_list_t percept = new symbol_list_t(0); //agent.preceptBits ());
agent.genPerceptAndUpdate(agent.rng, percept);
double reward = agent.rewardFromPercept(percept);
// playout the remainder of the sequence
reward += playout(agent, agent.rng, agent.horizon() - 1);
rfirst[i] += reward;
rsecond[i] += 1.0;
agent.modelRevert(mu);
//assert(start_hist_len == agent.historySize());
total_samples++;
}
elapsed = DateTime.Now - ti;
} while (Math.Abs(elapsed.TotalMilliseconds) < time_limit_ms);
// determine best arm, breaking ties arbitrarily
double best = double.NegativeInfinity;
action_t best_action = 0;
for (int i = 0; i < (int)agent.numActions(); i++)
{
// assert(r[i].second > 0.0);
double noise = agent.rng.NextDouble() * 0.0001;
double x = rfirst[i] / rsecond[i] + noise;
if (x > best)
{
best = x;
best_action = (UInt64)i;
}
}
//agent.logbox.Items.Add( "naive monte-carlo decision based on " + total_samples + " samples.");
for (int i = 0; i < (int)agent.numActions(); i++)
{
//agent.logbox.Items.Add("action " + i + ": " +( rfirst[i] / rsecond[i]));
}
//agent.logbox.Items.Add(" best_action:" + best_action);
return(best_action);
}
// revert the agent's internal model of the world
// to that of a previous time cycle, false on failure
public bool modelRevert(ModelUndo mu)
{
// return false; // TODONE: implement
// assert(m_ct->historySize() > mu.historySize());
// assert(!m_use_self_model || m_self_model->historySize() > mu.historySize());
if (m_time_cycle < mu.age())
{
return(false);
}
// agent properties must be reverted before context update,
// since the predicates that depend on the context may
// depend on them
m_time_cycle = mu.age();
m_hash = mu.hash();
m_total_reward = mu.reward();
m_last_update_percept = mu.lastUpdatePercept();
// revert the context tree and history back to it's previous state
if (mu.lastUpdatePercept())
{ // if we are undoing an action
m_ct.revertHistory(mu.historySize());
if (m_use_self_model)
{
Int64 end_size = (Int64)m_self_model.historySize();
for (Int64 i = 0; i < (Int64)end_size - (Int64)mu.historySize(); i++)
{
m_self_model.revert();
}
}
}
else
{
// if we are undoing an observation / reward
Int64 end_size = (Int64)m_ct.historySize();
Int64 percept_bits = (Int64)(m_obs_bits + m_rew_bits);
Int64 lim = (Int64)end_size - (Int64)mu.historySize();
for (Int64 i = 0; i < (Int64)end_size - (Int64)mu.historySize(); i++)
{
//ORIGINAL :: m_ct.revert(percept_bits - i - 1);
Int64 offset = percept_bits - i - 1;
m_ct.revert();
for (Int64 ix = 0; ix < (Int64)m_ct.size(); ix++)
{
if (ix != offset)
{
m_ct.m_history.pop_back();
}
}
}
if (m_use_self_model)
{
m_self_model.revertHistory(mu.historySize());
}
}
//assert(!m_use_self_model || m_self_model.historySize() == m_ct.historySize());
return(true);
}
