Sampler for this object is not defined

[logankilpatrick]

Hey Zach,

I am getting the following error when using POMCPOW with some other use cases:

ERROR: LoadError: ArgumentError: Sampler for this object is not defined
Stacktrace:
 [1] Random.Sampler(::Type{Random.MersenneTwister}, ::Random.SamplerTrivial{LPDM.LPDMBelief{SHERPA.RPState,SHERPA.RPAction,SHERPA.RPObservation},Any}, ::Val{1}) at /Users/sabae/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.3/Random/src/Random.jl:145
 [2] Random.Sampler(::Random._GLOBAL_RNG, ::Random.SamplerTrivial{LPDM.LPDMBelief{SHERPA.RPState,SHERPA.RPAction,SHERPA.RPObservation},Any}, ::Val{1}) at /Users/sabae/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.3/Random/src/Random.jl:139
 [3] rand(::Random._GLOBAL_RNG, ::Random.SamplerTrivial{LPDM.LPDMBelief{SHERPA.RPState,SHERPA.RPAction,SHERPA.RPObservation},Any}) at /Users/sabae/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.3/Random/src/Random.jl:253 (repeats 2 times)
 [4] search(::POMCPOW.POMCPOWPlanner{SHERPA.Synthesis.SynthesisPOMDP{SHERPA.Synthesis.SynthesisBoundsConfig},POMCPOW.POWNodeFilter,POMCPOW.MaxUCB,MCTS.RandomActionGenerator{Random._GLOBAL_RNG},BasicPOMCP.SolvedPORollout{POMDPPolicies.RandomPolicy{Random._GLOBAL_RNG,SHERPA.Synthesis.SynthesisPOMDP{SHERPA.Synthesis.SynthesisBoundsConfig},BeliefUpdaters.NothingUpdater},BeliefUpdaters.NothingUpdater,Random._GLOBAL_RNG},Int64,Float64,POMCPOW.POMCPOWSolver{Random._GLOBAL_RNG}}, ::POMCPOW.POMCPOWTree{POMCPOW.POWNodeBelief{SHERPA.RPState,SHERPA.RPAction,SHERPA.RPObservation,SHERPA.Synthesis.SynthesisPOMDP{SHERPA.Synthesis.SynthesisBoundsConfig}},SHERPA.RPAction,SHERPA.RPObservation,LPDM.LPDMBelief{SHERPA.RPState,SHERPA.RPAction,SHERPA.RPObservation}}, ::Dict{Symbol,Any}) at /Users/logankilpatrick/.julia/packages/POMCPOW/7FCnV/src/planner2.jl:62
 [5] #action_info#5(::Bool, ::typeof(POMDPModelTools.action_info), ::POMCPOW.POMCPOWPlanner{SHERPA.Synthesis.SynthesisPOMDP{SHERPA.Synthesis.SynthesisBoundsConfig},POMCPOW.POWNodeFilter,POMCPOW.MaxUCB,MCTS.RandomActionGenerator{Random._GLOBAL_RNG},BasicPOMCP.SolvedPORollout{POMDPPolicies.RandomPolicy{Random._GLOBAL_RNG,SHERPA.Synthesis.SynthesisPOMDP{SHERPA.Synthesis.SynthesisBoundsConfig},BeliefUpdaters.NothingUpdater},BeliefUpdaters.NothingUpdater,Random._GLOBAL_RNG},Int64,Float64,POMCPOW.POMCPOWSolver{Random._GLOBAL_RNG}}, ::LPDM.LPDMBelief{SHERPA.RPState,SHERPA.RPAction,SHERPA.RPObservation}) at /Users/logankilpatrick/.julia/packages/POMCPOW/7FCnV/src/planner2.jl:34
 [6] action_info at /Users/logankilpatrick/.julia/packages/POMCPOW/7FCnV/src/planner2.jl:28 [inlined]
 [7] action at /Users/logankilpatrick/.julia/packages/POMCPOW/7FCnV/src/planner2.jl:44 [inlined]

This happens when I do: a = POMDPs.action(policy, current_b) in my code. Any suggestions to resolve this?

[zsunberg]

Hi @logankilpatrick,

Sampler not defined errors mean that rand was not properly implemented for some object. Maybe in this case, rand is not implemented for the belief? What type is current_b?