No method matching states(::MyMDP)

[maxmouchet]

Hi,

When I run @requirements_info on this minimal example, it says states and n_states are not defined. But they are. Or have I missed something ?

This is on Julia v0.5 and POMDPs v0.4.1.

using POMDPs
using DiscreteValueIteration

type MyMDP <: MDP{Int64, Bool} end

states(::MyMDP) = [0, 1, 2, 3]
n_states(::MyMDP) = 4

@requirements_info ValueIterationSolver() MyMDP()

For solve(::ValueIterationSolver, ::Union{MDP,POMDP}):
  [✓] discount(::MyMDP)
  [X] n_states(::MyMDP)
  [✓] n_actions(::MyMDP)
  [X] transition(::MyMDP, ::Int64, ::Bool)
  [X] reward(::MyMDP, ::Int64, ::Bool, ::Int64)
  [✓] state_index(::MyMDP, ::Int64)
  [✓] action_index(::MyMDP, ::Bool)
  [✓] actions(::MyMDP, ::Int64)
  WARNING: Some requirements may not be shown because a MethodError was thrown.
For ordered_states(::Union{MDP,POMDP}) (in solve(::ValueIterationSolver, ::Union{MDP,POMDP})):
  [X] states(::MyMDP)

[zsunberg]

Hi Maxime,

You need to write a new method for states in the POMDPs namespace. You need to either need to

1) explicitly import the function from POMDPs, i.e. use importall POMDPs instead of using POMDPs, or 2) use the fully-qualified method name, i.e.

using POMDPs

type MyMDP <: MDP{Int64, Bool} end

POMDPs.states(::MyMDP) = [0, 1, 2, 3]

Hope that helps!

[maxmouchet]

Ok, I understand, it's working now. Thanks for your time!

[zsunberg]

Cool, good to hear you got it working