added some exceptions, made visualization better

src/POMCP.jl

@@ -46,11 +46,17 @@ export
     ParticleReinvigorator,
     reinvigorate!,
     handle_unseen_observation,
-    DefaultReinvigoratorStub
+    DefaultReinvigoratorStub,
+
+    NoDecision,
+    AllSamplesTerminal,
+    ExceptionRethrow,
+    default_action
 
 
 include("tree.jl")
 include("particle_filter.jl")
+include("exceptions.jl")
 
 abstract AbstractPOMCPSolver <: POMDPs.Solver
 
@@ -108,6 +114,13 @@ Fields:
         Number of actions to be considered at each node.
         If <= 0, the entire action space will be considered.
         default: 0
+
+    default_action::Any
+        Function, action, or Policy used to determine the action if POMCP fails with exception `ex`.
+        If this is a Function `f`, `f(belief, ex)` will be called.
+        If this is a Policy `p`, `action(p, belief)` will be called.
+        If it is an object `a`, `default_action(a, belief, ex) will be called, and
+        if this method is not implemented, `a` will be returned directly.
 """
 type POMCPSolver <: AbstractPOMCPSolver
     eps::Float64 # will stop simulations when discount^depth is less than this
@@ -123,6 +136,7 @@ type POMCPSolver <: AbstractPOMCPSolver
     init_N::Any
 
     num_sparse_actions::Int # = 0 or less if not used
+    default_action::Any
 end 
 
 """
@@ -168,8 +182,8 @@ Fields:
 
     k_action::Float64
     alpha_action::Float64
-    k_state::Float64
-    alpha_state::Float64
+    k_observation::Float64
+    alpha_observation::Float64
         These constants control the double progressive widening. A new observation
         or action will be added if the number of children is less than or equal to kN^alpha.
         defaults: k:10, alpha:0.5
@@ -195,6 +209,13 @@ Fields:
         If this is an object `o`, `next_action(o, pomdp, b, h)` will be called.
         default: RandomActionGenerator(rng)
 
+    default_action::Any
+        Function, action, or Policy used to determine the action if POMCP fails with exception `ex`.
+        If this is a Function `f`, `f(belief, ex)` will be called.
+        If this is a Policy `p`, `action(p, belief)` will be called.
+        If it is an object `a`, `default_action(a, belief, ex) will be called, and
+        if this method is not implemented, `a` will be returned directly.
+
 For more information on the k and alpha parameters, see Couëtoux, A., Hoock, J.-B., Sokolovska, N., Teytaud, O., & Bonnard, N. (2011). Continuous Upper Confidence Trees. In Learning and Intelligent Optimization. Rome, Italy. Retrieved from http://link.springer.com/chapter/10.1007/978-3-642-25566-3_32
 """
 type POMCPDPWSolver <: AbstractPOMCPSolver
@@ -216,6 +237,7 @@ type POMCPDPWSolver <: AbstractPOMCPSolver
     init_V::Any
     init_N::Any
     next_action::Any
+    default_action::Any
 end
 
 """

src/constructor.jl

@@ -14,7 +14,8 @@ function POMCPSolver(;eps=0.01,
                       estimate_value=RolloutEstimator(POMDPToolbox.RandomSolver()),
                       init_V=0.0,
                       init_N=0,
-                      num_sparse_actions=0)
+                      num_sparse_actions=0,
+                      default_action=ExceptionRethrow())
 
     return POMCPSolver(eps,
                        max_depth,
@@ -25,7 +26,8 @@ function POMCPSolver(;eps=0.01,
                        estimate_value,
                        init_V,
                        init_N,
-                       num_sparse_actions)
+                       num_sparse_actions,
+                       default_action)
 end
 
 """
@@ -49,7 +51,8 @@ function POMCPDPWSolver(;eps=0.01,
                       k_action::Float64=10.,
                       init_V=0.0,
                       init_N=0,
-                      next_action=RandomActionGenerator())
+                      next_action=RandomActionGenerator(),
+                      default_action=ExceptionRethrow())
 
     return POMCPDPWSolver(eps,
                        max_depth,
@@ -65,5 +68,6 @@ function POMCPDPWSolver(;eps=0.01,
                        k_action,
                        init_V,
                        init_N,
-                       next_action)
+                       next_action,
+                       default_action)
 end

src/exceptions.jl

@@ -0,0 +1,26 @@
+abstract NoDecision <: Exception
+Base.show(io::IO, nd::NoDecision) = print(io, """
+    POMCP failed to choose an action because the following exception was thrown:
+    $nd
+
+    To specify an action for this case, use the default_action solver parameter.
+    """)
+
+immutable AllSamplesTerminal <: NoDecision
+    belief
+end
+Base.show(io::IO, ast::AllSamplesTerminal) = print(io, """
+    POMCP failed to choose an action because all states sampled from the belief were terminal.
+
+    To see the belief, catch this exception as ex and see ex.belief.
+    
+    To specify an action for this case, use the default_action solver parameter.
+    """)
+
+
+immutable ExceptionRethrow end
+
+default_action(::ExceptionRethrow, belief, ex) = rethrow(ex)
+default_action(f::Function, belief, ex) = f(belief, ex)
+default_action(p::POMDPs.Policy, belief, ex) = action(p, belief)
+default_action(o, belief, ex) = o

src/solver.jl

@@ -14,7 +14,12 @@ function create_policy{S}(solver::Union{POMCPSolver,POMCPDPWSolver}, pomdp::POMD
 end
 
 function action(policy::POMCPPlanner, belief, a=nothing)
-    return search(policy, belief, policy.solver.tree_queries)
+    try
+        a = search(policy, belief, policy.solver.tree_queries)
+    catch ex
+        a = default_action(policy.solver.default_action, belief, ex)
+    end
+    return a
 end
 
 """
@@ -42,19 +47,28 @@ function search{RootBelief}(pomcp::POMCPPlanner, belief::RootBelief, tree_querie
 end
 
 function search(pomcp::POMCPPlanner, b::BeliefNode, tree_queries)
-    #XXX hack
+    # XXX hack
     pomcp._tree_ref = b
     # end hack
 
+    all_terminal = true
     for i in 1:tree_queries
         s = rand(pomcp.solver.rng, b)
-        simulate(pomcp, b, s, 0)
-        b.N += 1
+        if !POMDPs.isterminal(pomcp.problem, s)
+            simulate(pomcp, b, s, 0)
+            b.N += 1
+            all_terminal = false
+        end
+    end
+
+    if all_terminal
+        throw(AllSamplesTerminal(b.B))
     end
 
-    best_V = -Inf
-    local best_node # guessing that type stability is not important enough to make a difference at this point
-    for node in values(b.children)
+    best_node = first(values(b.children))
+    best_V = best_node.V
+    @assert !isnan(best_V)
+    for node in collect(values(b.children))[2:end]
         if node.V >= best_V
             best_V = node.V
             best_node = node

src/visualization.jl

@@ -1,10 +1,12 @@
 import JSON
-import MCTS: node_tag, tooltip_tag
+import MCTS: node_tag, tooltip_tag, blink
 
-type POMCPTreeVisualizer
+type POMCPTreeVisualizer <: AbstractTreeVisualizer
     node::BeliefNode
 end
 
+blink(n::BeliefNode) = blink(POMCPTreeVisualizer(n))
+
 typealias NodeDict Dict{Int, Dict{String, Any}}
 
 function create_json(v::POMCPTreeVisualizer)
@@ -69,35 +71,3 @@ function recursive_push!(nd::NodeDict, n::ActNode, parent_id=-1)
     end
     return nd
 end
-
-function Base.show(f::IO, ::MIME"text/html", visualizer::POMCPTreeVisualizer)
-    json, root_id = create_json(visualizer)
-    # write("/tmp/tree_dump.json", json)
-    css = @compat readstring(joinpath(Pkg.dir("MCTS"), "src", "tree_vis.css"))
-    js = @compat readstring(joinpath(Pkg.dir("MCTS"), "src", "tree_vis.js"))
-    div = "treevis$(randstring())"
-
-    html_string = """
-        <div id="$div">
-        <style>
-            $css
-        </style>
-        <script>
-            (function(){
-            var treeData = $json;
-            var rootID = $root_id;
-            var div = "$div";
-            $js
-            })();
-        </script>
-        </div>
-    """
-    # html_string = "visualization doesn't work yet :("
-
-    # for debugging
-    # outfile  = open("/tmp/pomcp_debug.html","w")
-    # write(outfile,html_string)
-    # close(outfile)
-
-    println(f,html_string)
-end