Sim Agent

The observation of agents in Pommerman is not the same as the game state. Not only can the items (such as Extra Bomb item) not be seen, but agents cannot know the number of ammo others have with only the current observation. However, we can simulate most of them by preceding observations, which the SimAgent in this repo does.

However, there are some inevitable limitations which are explained here, which SimAgent has tried to diminish.

Getting Started

Creating environment

git clone --recurse-submodules git@github.com:guikarist/sim-agent.git
cd sim-agent
conda env create -f pommerman/env.yml
conda activate pommerman

Usage

To use the Sim Agent, all you need to do is:

1. Subclass the SimAgent class in sim_agent.py.
2. Implement the _act(self, obs, action_space) method. Or after investigating the logics, you can override act(self, obs, action_space) for advanced usages.

Details of Sim Agent

The simulated information of SimAgent is:

• List[_Item] self._items

  A list of items which are observable on the board. The information of _Item() is:

  • _Pos self.pos The position of an item
  • _ItemType self.type The type of an item

• List[_Bomb] self._bombs

  A list of bombs which are observable on the board. The information of _Bomb() is:

  • _Pos self.pos The position of a bomb
  • _Agent self.bomber The bomber of a bomb
  • BlastStrengthType self.blast_strength The blast strength of a bomb
  • ActionType self.first_moving_direction The first moving direction of a bomb
  • bool self.has_been_moved The moving state of a bomb (True once the bomb has been moved before)
  • BombLifeType self.life The life of a bomb (This may be INACCURATE when the bomb has_been_moved)

• List[_Agent] self._agents

  A list of alive agents in the game. The information of _Agent() is:

  • _Pos self.pos: The agent position
  • AgentIdType self.id The agent id (e.g., 0)
  • AgentValueType self.value The agent value (e.g., 10)
  • AmmoType self.ammo The number of ammo of an agent (This may be INACCURATE)
  • bool self.can_kick: The ability to kick bombs of an agent (This may be INACCURATE)
  • BlastStrengthType self.blast_strength: The blast strength of an anget (This may be INACCURATE)

Test

For the correctness of the simulation, tests are necessary.

Normal Test

This will test add_ability() of _Agent, games of one SimAgent with three RandomAgent, and games of one SimAgent with three SimpleAgent.

python test_sim_agent.py

Test with PlayerAgent

This will initialize games with one PlayerAgent, one SimAgent and two _IdleAgent (which does nothing but stop), where you can test manually by playing.

python test_sim_agent.py TestSimAgent._test_simulation_by_player_agent

Explanation for Inaccuracy

The simulation is impossible to be perfect and here is an example:

It is possible for an agent to get an item while no others see: if at some step, these three things happen at the same time: a box is destroyed by flame of bombs, an agent move to the position of this box and there is an item below this box.

Thus, when this kind of situations happen, these information of agent simulation cannot be accurate:

1. ammo
2. blast strength
3. the ability to kick a bomb

Reference

Pommerman Environment