BasicPOMCP application

[Etwari3]

Hello,

I was trying to apply BasicPOMCP to a problem in maintenance optimization. I got this message and could not find the bug.

ArgumentError: Sampler for this object is not defined

Stacktrace:
[1] Random.Sampler(#unused#::Type{TaskLocalRNG}, sp::Random.SamplerTrivial{Float64, Float64}, #unused#::Val{1})
@ Random C:\Users\ezrat\AppData\Local\Programs\Julia-1.7.2\share\julia\stdlib\v1.7\Random\src\Random.jl:146
[2] Random.Sampler(rng::Random._GLOBAL_RNG, x::Random.SamplerTrivial{Float64, Float64}, r::Val{1})
@ Random C:\Users\ezrat\AppData\Local\Programs\Julia-1.7.2\share\julia\stdlib\v1.7\Random\src\Random.jl:140
[3] rand(rng::Random._GLOBAL_RNG, X::Random.SamplerTrivial{Float64, Float64}) (repeats 2 times)
@ Random C:\Users\ezrat\AppData\Local\Programs\Julia-1.7.2\share\julia\stdlib\v1.7\Random\src\Random.jl:254
[4] search(p::POMCPPlanner{PipeCS, BasicPOMCP.SolvedPORollout{RandomPolicy{Random._GLOBAL_RNG, PipeCS, NothingUpdater}, NothingUpdater, Random._GLOBAL_RNG}, Random._GLOBAL_RNG}, b::Float64, t::BasicPOMCP.POMCPTree{Int64, Int64}, info::Dict{Symbol, Any})
@ BasicPOMCP C:\Users\ezrat.julia\packages\BasicPOMCP\1adcm\src\solver.jl:30
[5] action_info(p::POMCPPlanner{PipeCS, BasicPOMCP.SolvedPORollout{RandomPolicy{Random._GLOBAL_RNG, PipeCS, NothingUpdater}, NothingUpdater, Random._GLOBAL_RNG}, Random._GLOBAL_RNG}, b::Float64; tree_in_info::Bool)
@ BasicPOMCP C:\Users\ezrat.julia\packages\BasicPOMCP\1adcm\src\solver.jl:6
[6] action_info
@ C:\Users\ezrat.julia\packages\BasicPOMCP\1adcm\src\solver.jl:2 [inlined]
[7] action(p::POMCPPlanner{PipeCS, BasicPOMCP.SolvedPORollout{RandomPolicy{Random._GLOBAL_RNG, PipeCS, NothingUpdater}, NothingUpdater, Random._GLOBAL_RNG}, Random._GLOBAL_RNG}, b::Float64)
@ BasicPOMCP C:\Users\ezrat.julia\packages\BasicPOMCP\1adcm\src\solver.jl:19
[8] top-level scope
@ In[13]:2
[9] eval
@ .\boot.jl:373 [inlined]
[10] include_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
@ Base .\loading.jl:1196

Can you please give some directions?

[zsunberg]

Hi @Etwari3 , this error is occuring when POMCP attempts to sample a state from the belief at the root node in solver.jl line 30. The belief object is not sampleable.

Can you share your implementation for the initialstate function? A common mistake is to return a single state from initialstate rather than a distribution. It appears that you may be returning a float rather than a distribution. I'd suggest using POMDPTools.Uniform or POMDPTools.Deterministic.

[Etwari3]

Hi @zsunberg
Thank you. It has worked.