Fix metric resizing (#232)

* Fix metric resizing

* Make suggested changes

* Bump version number

Project.toml

@@ -1,6 +1,6 @@
 name = "AdvancedHMC"
 uuid = "0bf59076-c3b1-5ca4-86bd-e02cd72cde3d"
-version = "0.2.26"
+version = "0.2.27"
 
 [deps]
 ArgCheck = "dce04be8-c92d-5529-be00-80e4d2c0e197"

src/metric.jl

@@ -76,6 +76,12 @@ renew(ue::DenseEuclideanMetric, M⁻¹) = DenseEuclideanMetric(M⁻¹)
 Base.size(e::DenseEuclideanMetric, dim...) = size(e._temp, dim...)
 Base.show(io::IO, dem::DenseEuclideanMetric) = print(io, "DenseEuclideanMetric(diag=$(_string_M⁻¹(dem.M⁻¹)))")
 
+# getname functions
+for T in (UnitEuclideanMetric, DiagEuclideanMetric, DenseEuclideanMetric)
+    @eval getname(::Type{<:$T}) = $T
+end
+getname(m::T) where {T<:AbstractMetric} = getname(T)
+
 # `rand` functions for `metric` types.
 
 function _rand(

src/sampler.jl

@@ -20,7 +20,7 @@ end
 function resize(h::Hamiltonian, θ::AbstractVecOrMat{T}) where {T<:AbstractFloat}
     metric = h.metric
     if size(metric) != size(θ)
-        metric = typeof(metric)(size(θ))
+        metric = getname(metric)(size(θ))
         h = reconstruct(h, metric=metric)
     end
     return h

test/metric.jl

@@ -17,3 +17,19 @@ using Test, Random, AdvancedHMC
         @test all_same
     end
 end
+
+@testset "Resize metric" begin
+    D = 10
+    rng = MersenneTwister(1)
+    θ = randn(rng, D)
+    ℓπ(θ) = 1
+    for metric in [
+        UnitEuclideanMetric(1),
+        DiagEuclideanMetric(1),
+        DenseEuclideanMetric(1)
+    ]
+        h = Hamiltonian(metric, ℓπ, ℓπ)
+        h = AdvancedHMC.resize(h, θ)
+        @test size(h.metric) == size(θ)
+    end
+end