Merge pull request #47 from JuliaPOMDP/bool

added bool distribution

README.md

@@ -53,6 +53,9 @@ Provides a sparse categorical distribution `SparseCat`. This distribution simply
 #### [`weighted_iteration.jl`](src/distributions/weighted_iteration.jl)
 Function for iterating through pairs of values and their probabilities in a distribution.
 
+#### [`bool.jl`](src/distributions/bool.jl)
+Distribution over an outcome being true. Create with `BoolDistribution(p_true)`. Obviously, the probability of false is simply `1 - p_true`.
+
 ### Model
 #### [`info.jl`](src/model/info.jl)
 Contains a small interface for outputting extra information (usually a `Dict` or `nothing`) from simulations.

src/POMDPToolbox.jl

@@ -43,6 +43,7 @@ export
     product
 include("beliefs/discrete.jl")
 
+
 export
     PreviousObservationUpdater,
     FastPreviousObservationUpdater,
@@ -169,6 +170,10 @@ export
     SparseCat
 include("distributions/sparse_cat.jl")
 
+export
+    BoolDistribution
+include("distributions/bool.jl")
+
 # testing
 export test_solver
 include("testing/solver.jl")

src/distributions/bool.jl

@@ -0,0 +1,21 @@
+"""
+    BoolDistribution
+
+A distribution that provides the probabilities of true or false. 
+Can construct with `BoolDistribution(p_true)`.
+"""
+struct BoolDistribution
+    p::Float64 # probability of true
+end
+
+pdf(d::BoolDistribution, s::Bool) = s ? d.p : 1.0-d.p
+
+rand(rng::AbstractRNG, d::BoolDistribution) = rand(rng) <= d.p
+
+iterator(d::BoolDistribution) = [true, false]
+
+==(d1::BoolDistribution, d2::BoolDistribution) = d1.p == d2.p
+
+Base.hash(d::BoolDistribution) = hash(d.p)
+
+Base.length(d::BoolDistribution) = 2

test/runtests.jl

@@ -22,4 +22,5 @@ include("test_implementations.jl")
 include("test_distributions_jl.jl")
 include("test_weighted_iteration.jl")
 include("test_sparse_cat.jl")
+include("test_bool.jl")
 include("test_info.jl")

test/test_bool.jl

@@ -0,0 +1,21 @@
+using POMDPToolbox
+using Base.Test
+
+# Hack to get this to build with POMDPModels
+# this can be removed once BoolDistribution is removed from POMDPModels
+BoolDistribution = POMDPToolbox.BoolDistribution
+
+# testing constructor and pdf
+d = BoolDistribution(0.3)
+@test pdf(d, true) == 0.3
+@test pdf(d, false) == 0.7
+
+# testing iterator
+@test iterator(d) == [true, false]
+
+# testing ==
+d2 = BoolDistribution(0.3)
+@test d == d2
+
+# testing hash
+@test hash(d) == hash(d.p)