Add new environment: CollectGems (#37)

* add CollectGems environment

* add gif for CollectGems environment

* move Gem object definition to objects.jl

README.md

@@ -46,6 +46,10 @@ play(w;file_name="example.gif",frame_rate=5)
 
 <img src="https://github.com/JuliaReinforcementLearning/GridWorlds.jl/raw/master/docs/src/assets/img/DoorKey.gif" width="300px">
 
+- [x] CollectGems
+
+<img src="https://github.com/JuliaReinforcementLearning/GridWorlds.jl/raw/master/docs/src/assets/img/CollectGems.gif" width="300px">
+
 ### Needs improvement
 
 - [ ] Add test cases

src/envs/collectgems.jl

@@ -0,0 +1,50 @@
+export CollectGems
+
+mutable struct CollectGems <: AbstractGridWorld
+    world::GridWorldBase{Tuple{Empty,Wall,Gem}}
+    agent_pos::CartesianIndex{2}
+    agent::Agent
+    num_gem_init::Int
+    num_gem_current::Int
+end
+
+function CollectGems(;n=8, agent_start_pos=CartesianIndex(2,2), agent_start_dir=RIGHT)
+    objects = (EMPTY, WALL, GEM)
+    w = GridWorldBase(objects, n, n)
+
+    w[EMPTY, 2:n-1, 2:n-1] .= true
+    w[WALL, [1,n], 1:n] .= true
+    w[WALL, 1:n, [1,n]] .= true
+
+    w[GEM, 1:n, 1:n] .= false
+    num_gem_init = n - 1
+    num_gem_current = num_gem_init
+
+    gem_placed = 0
+    while gem_placed < num_gem_init
+        gem_pos = CartesianIndex(rand(2:n-1), rand(2:n-1))
+        if (gem_pos == agent_start_pos) || (w[GEM, gem_pos] == true)
+            continue
+        else
+            w[GEM, gem_pos] = true
+            w[EMPTY, gem_pos] = false
+            gem_placed = gem_placed + 1
+        end
+    end
+
+    CollectGems(w, agent_start_pos, Agent(dir=agent_start_dir), num_gem_init, num_gem_current)
+end
+
+function (w::CollectGems)(::MoveForward)
+    dir = get_dir(w.agent)
+    dest = dir(w.agent_pos)
+    if !w.world[WALL, dest]
+        w.agent_pos = dest
+        if w.world[GEM, dest]
+            w.world[GEM, dest] = false
+            w.world[EMPTY, dest] = true
+            w.num_gem_current = w.num_gem_current - 1
+        end
+    end
+    w
+end

src/envs/envs.jl

@@ -2,3 +2,4 @@ include("empty.jl")
 include("fourrooms.jl")
 include("gotodoor.jl")
 include("doorkey.jl")
+include("collectgems.jl")

src/objects.jl

@@ -1,5 +1,5 @@
-export COLORS, MOVE_FORWARD, TURN_LEFT, TURN_RIGHT, UP, DOWN, LEFT, RIGHT, LRUD, EMPTY, WALL, GOAL
-export MoveForward, AbstractObject, Empty, Wall, Goal, Door, Agent
+export COLORS, MOVE_FORWARD, TURN_LEFT, TURN_RIGHT, UP, DOWN, LEFT, RIGHT, LRUD, EMPTY, WALL, GOAL, GEM
+export MoveForward, AbstractObject, Empty, Wall, Goal, Door, Gem, Agent
 export get_color
 
 using Crayons
@@ -79,6 +79,11 @@ Key(c) = Key{c}()
 Base.convert(::Type{Char}, ::Key) = '⚷'
 get_color(::Key{C}) where C = C
 
+struct Gem <: AbstractObject end
+const GEM = Gem()
+Base.convert(::Type{Char}, ::Gem) = '♦'
+get_color(::Gem) = :magenta
+
 Base.@kwdef mutable struct Agent <: AbstractObject
     color::Symbol=:red
     dir::LRUD