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added FrozenLake environment #135

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138 changes: 138 additions & 0 deletions src/envs/FrozenLakeEnv.jl
Original file line number Diff line number Diff line change
@@ -0,0 +1,138 @@

export FrozenLakeEnv

Base.@kwdef mutable struct frozenlakeEnv <: AbstractEnv
# lake: 3 is the spawn point, 1 is the goal and 2 are obstacles.
lake::Array{Int8,2} = [1 0 0 0 0
0 2 0 2 0
0 0 0 2 0
0 2 0 0 0
0 0 0 0 3]
reward::Union{Nothing, Float64} = 0
observation::Int = 24
is_terminated = false
num_steps::Int8 = 0
MAX_STEPS::Int8 = 100
end

RLBase.action_space(env::frozenlakeEnv) = (:up, :right, :down, :left)

begin
RLBase.state(env::frozenlakeEnv) = env.observation
RLBase.state_space(env::frozenlakeEnv) = collect(0:24)
RLBase.is_terminated(env::frozenlakeEnv) = env.is_terminated
end

function RLBase.reset!(env::frozenlakeEnv)
env.reward = 0
env.observation = 24
env.num_steps = 0
env.is_terminated = false
end

function moveDeterministic(action::String, observation)
if action == "up"
observation = clamp((observation÷5)-1, 0, 4)*5 + (observation - 5*(observation÷5))
elseif action == "down"
observation = clamp((observation÷5)+1, 0, 4)*5 + (observation - 5*(observation÷5))
elseif action == "left"
observation = observation÷5*5 + clamp((observation - 5*(observation÷5))-1, 0, 4)
elseif action == "right"
observation = observation÷5*5 + clamp((observation - 5*(observation÷5))+1, 0, 4)
end
return observation
end


function (env::frozenlakeEnv)(action)
r = rand()
env.num_steps += 1
if action == :up
if r < 1/3
# goes up
env.observation = moveDeterministic("up", env.observation)
elseif r < 2/3
# goes left
env.observation = moveDeterministic("left", env.observation)
else
# goes right
env.observation = moveDeterministic("left", env.observation)
end

elseif action == :right
if r < 1/3
# goes right
env.observation = moveDeterministic("right", env.observation)
elseif r < 2/3
# goes up
env.observation = moveDeterministic("up", env.observation)
else
# goes down
env.observation = moveDeterministic("down", env.observation)
end

elseif action == :down
if r < 1/3
# goes right
env.observation = moveDeterministic("right", env.observation)
elseif r < 2/3
# goes left
env.observation = moveDeterministic("left", env.observation)
else
# goes down
env.observation = moveDeterministic("down", env.observation)
end

elseif action == :left
if r < 1/3
# goes up
env.observation = moveDeterministic("up", env.observation)
elseif r < 2/3
# goes left
env.observation = moveDeterministic("left", env.observation)
else
# goes down
env.observation = moveDeterministic("down", env.observation)
end
else
@error "unknown action of $action"
end

obdiv5 = env.observation÷5
if env.num_steps>env.MAX_STEPS
env.is_terminated = true
end
if env.lake[obdiv5+1, env.observation - (5*obdiv5) + 1] == 0 || env.lake[obdiv5+1, env.observation - (5*obdiv5) + 1] == 3
env.reward-=0.01
elseif env.lake[obdiv5+1, env.observation - (5*obdiv5) + 1] == 2
env.is_terminated = true
env.reward-=1
elseif env.lake[obdiv5+1, env.observation - (5*obdiv5) + 1] == 1
env.is_terminated = true
env.reward+=5
end
# println(env.reward," ", env.num_steps, " ", env.observation)
end

RLBase.reward(env::frozenlakeEnv) = env.reward

# Env = frozenlakeEnv()
# RLBase.test_runnable!(Env)
# begin
# run(RandomPolicy(action_space(Env)), Env, StopAfterEpisode(1))
# end

# begin
# hook = TotalRewardPerEpisode()
# run(RandomPolicy(action_space(Env)), Env, StopAfterEpisode(10), hook)
# plot(hook.rewards)
# end
# p = QBasedPolicy(
# learner = MonteCarloLearner(;
# approximator=TabularQApproximator(
# n_state = length(state_space(Env)),
# n_action = length(action_space(Env)),
# )
# ),
# explorer = EpsilonGreedyExplorer(0.1)
# )