made minimal_example easier to understand

notebooks/Minimal_Example.ipynb

@@ -217,7 +217,7 @@
    "source": [
     "## Reliable Belief Updates\n",
     "\n",
-    "This model has a small enough observation space to be used with the default  unweighted rejection-based particle filter. In most cases we need to use a weighted particle filter, which will require definition of the observation distribution."
+    "By default, if the POMDP does not have an explicit observation model implemented (`POMDPs.observation()` or `ParticleFilters.obs_weight()`), POMCP will attempt to use the unweighted rejection particle filter defined here: https://github.com/JuliaPOMDP/ParticleFilters.jl/blob/master/src/unweighted.jl. Our `LightDark1D` POMDP has a small enough observation space for that to work, but in most cases, we will need to use a weighted particle filter, which will require definition of the observation distribution."
    ]
   },
   {

src/BasicPOMCP.jl

@@ -78,9 +78,9 @@ Partially Observable Monte Carlo Planning Solver. Options are set using the keyw
 
     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 Function `f`, `f(pomdp, 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 it is an object `a`, `default_action(a, pomdp, belief, ex) will be called, and
         if this method is not implemented, `a` will be returned directly.
 
     rng::AbstractRNG

src/exceptions.jl

@@ -20,10 +20,11 @@ Base.show(io::IO, ast::AllSamplesTerminal) = print(io, """
 
 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(a, belief, ex) = a
+default_action(::ExceptionRethrow, pomdp, belief, ex) = rethrow(ex)
+default_action(f::Function, pomdp, belief, ex) = f(belief, ex)
+default_action(p::POMDPs.Policy, pomdp, belief, ex) = action(p, belief)
+default_action(s::POMDPs.Solver, pomdp, belief, ex) = action(solve(s, pomdp), belief)
+default_action(a, pomdp, belief, ex) = a
 
 """
     ReportWhenUsed(a)
@@ -34,7 +35,7 @@ immutable ReportWhenUsed{T}
     a::T
 end
 
-function default_action(r::ReportWhenUsed, belief, ex)
+function default_action(r::ReportWhenUsed, pomdp, belief, ex)
     showerror(STDERR, ex)
     warn("Using default action $(r.a)")
     return r.a

src/solver.jl

@@ -6,7 +6,7 @@ function action(p::POMCPPlanner, b)
         p._tree = Nullable(tree)
     catch ex
         # Note: this might not be type stable, but it shouldn't matter too much here
-        a = convert(action_type(p.problem), default_action(p.solver.default_action, b, ex))
+        a = convert(action_type(p.problem), default_action(p.solver.default_action, p.problem, b, ex))
     end
     return a
 end