ReadMe for consctructors

src/abstractmcmc.jl

@@ -271,47 +271,62 @@ end
 
 #########
 
+function make_step_size(
+    rng::Random.AbstractRNG,
+    spl::HMCSampler,
+    hamiltonian::Hamiltonian,
+    init_params,
+)
+    return spl.κ.τ.integrator.ϵ
+end
+
 function make_step_size(
     rng::Random.AbstractRNG,
     spl::AbstractHMCSampler,
     hamiltonian::Hamiltonian,
     init_params,
 )
-    ϵ = spl.init_ϵ
-    if iszero(ϵ)
-        ϵ = find_good_stepsize(rng, hamiltonian, init_params)
-        T = sampler_eltype(spl)
-        ϵ = T(ϵ)
-        @info string("Found initial step size ", ϵ)
-    end
-    return ϵ
+    T = sampler_eltype(spl)
+    return make_step_size(rng, spl.integrator, T, hamiltonian, init_params)
+
 end
 
 function make_step_size(
     rng::Random.AbstractRNG,
-    spl::HMCSampler,
+    integrator::AbstractIntegrator,
+    T::Type,
     hamiltonian::Hamiltonian,
     init_params,
 )
-    return spl.κ.τ.integrator.ϵ
+    return integrator.ϵ
+end
+
+function make_step_size(
+    rng::Random.AbstractRNG,
+    integrator::Symbol,
+    T::Type,
+    hamiltonian::Hamiltonian,
+    init_params,
+)
+    ϵ = find_good_stepsize(rng, hamiltonian, init_params)
+    @info string("Found initial step size ", ϵ)
+    return T(ϵ)
 end
 
 make_integrator(spl::HMCSampler, ϵ::Real) = spl.κ.τ.integrator
 make_integrator(spl::AbstractHMCSampler, ϵ::Real) = make_integrator(spl.integrator, ϵ)
 make_integrator(i::AbstractIntegrator, ϵ::Real) = i
-make_integrator(i::Type{<:AbstractIntegrator}, ϵ::Real) = i
 make_integrator(i::Symbol, ϵ::Real) = make_integrator(Val(i), ϵ)
-make_integrator(i...) = error("Integrator $(typeof(i)) not supported.")
+make_integrator(@nospecialize(i), ::Real) = error("Integrator $i not supported.")
 make_integrator(i::Val{:leapfrog}, ϵ::Real) = Leapfrog(ϵ)
-make_integrator(i::Val{:jitteredleapfrog}, ϵ::Real) = JitteredLeapfrog(ϵ)
-make_integrator(i::Val{:temperedleapfrog}, ϵ::Real) = TemperedLeapfrog(ϵ)
+make_integrator(i::Val{:jitteredleapfrog}, ϵ::Real) = JitteredLeapfrog(ϵ, 0.1ϵ)
+make_integrator(i::Val{:temperedleapfrog}, ϵ::Real) = TemperedLeapfrog(ϵ, 1.0)
 
 #########
 
-make_metric(i...) = error("Metric $(typeof(i)) not supported.")
+make_metric(@nospecialize(i), T::Type, d::Int) = error("Metric $(typeof(i)) not supported.")
 make_metric(i::Symbol, T::Type, d::Int) = make_metric(Val(i), T, d)
 make_metric(i::AbstractMetric, T::Type, d::Int) = i
-make_metric(i::Type{AbstractMetric}, T::Type, d::Int) = i
 make_metric(i::Val{:diagonal}, T::Type, d::Int) = DiagEuclideanMetric(T, d)
 make_metric(i::Val{:unit}, T::Type, d::Int) = UnitEuclideanMetric(T, d)
 make_metric(i::Val{:dense}, T::Type, d::Int) = DenseEuclideanMetric(T, d)

src/constructors.jl

@@ -28,20 +28,18 @@ struct HMCSampler{T<:Real} <: AbstractHMCSampler{T}
     metric::AbstractMetric
     "[`AbstractAdaptor`](@ref)."
     adaptor::AbstractAdaptor
-    "Adaptation steps if any"
-    n_adapts::Int
 end
 
-function HMCSampler(κ, metric, adaptor; n_adapts = 0)
+function HMCSampler(κ, metric, adaptor)
     T = collect(typeof(metric).parameters)[1]
-    return HMCSampler{T}(κ, metric, adaptor, n_adapts)
+    return HMCSampler{T}(κ, metric, adaptor)
 end
 
 ############
 ### NUTS ###
 ############
 """
-    NUTS(n_adapts::Int, δ::Real; max_depth::Int=10, Δ_max::Real=1000, init_ϵ::Real=0)
+    NUTS(δ::Real; max_depth::Int=10, Δ_max::Real=1000, init_ϵ::Real=0, integrator = :leapfrog, metric = :diagonal)
 
 No-U-Turn Sampler (NUTS) sampler.
 
@@ -52,7 +50,7 @@ $(FIELDS)
 # Usage:
 
 ```julia
-NUTS(n_adapts=1000, δ=0.65)  # Use 1000 adaption steps, and target accept ratio 0.65.
+NUTS(δ=0.65)  # Use target accept ratio 0.65.
 ```
 """
 struct NUTS{T<:Real} <: AbstractHMCSampler{T}
@@ -62,24 +60,15 @@ struct NUTS{T<:Real} <: AbstractHMCSampler{T}
     max_depth::Int
     "Maximum divergence during doubling tree."
     Δ_max::T
-    "Initial step size; 0 means it is automatically chosen."
-    init_ϵ::T
     "Choice of integrator, specified either using a `Symbol` or [`AbstractIntegrator`](@ref)"
     integrator::Union{Symbol,AbstractIntegrator}
-    "Choice of initial metric, specified using a `Symbol` or `AbstractMetric`. The metric type will be preserved during adaption."
+    "Choice of initial metric;  `Symbol` means it is automatically initialised. The metric type will be preserved during automatic initialisation and adaption."
     metric::Union{Symbol,AbstractMetric}
 end
 
-function NUTS(
-    δ;
-    max_depth = 10,
-    Δ_max = 1000.0,
-    init_ϵ = 0.0,
-    integrator = :leapfrog,
-    metric = :diagonal,
-)
+function NUTS(δ; max_depth = 10, Δ_max = 1000.0, integrator = :leapfrog, metric = :diagonal)
     T = typeof(δ)
-    return NUTS(δ, max_depth, T(Δ_max), T(init_ϵ), integrator, metric)
+    return NUTS(δ, max_depth, T(Δ_max), integrator, metric)
 end
 
 ###########
@@ -97,29 +86,32 @@ $(FIELDS)
 # Usage:
 
 ```julia
-HMC(init_ϵ=0.05, n_leapfrog=10)
+HMC(init_ϵ=0.05, n_leapfrog=10, integrator = :leapfrog, metric = :diagonal)
 ```
 """
 struct HMC{T<:Real} <: AbstractHMCSampler{T}
-    "Initial step size; 0 means automatically searching using a heuristic procedure."
-    init_ϵ::T
     "Number of leapfrog steps."
     n_leapfrog::Int
     "Choice of integrator, specified either using a `Symbol` or [`AbstractIntegrator`](@ref)"
     integrator::Union{Symbol,AbstractIntegrator}
-    "Choice of initial metric, specified using a `Symbol` or `AbstractMetric`. The metric type will be preserved during adaption."
+    "Choice of initial metric;  `Symbol` means it is automatically initialised. The metric type will be preserved during automatic initialisation and adaption."
     metric::Union{Symbol,AbstractMetric}
 end
 
-function HMC(init_ϵ, n_leapfrog; integrator = :leapfrog, metric = :diagonal)
-    return HMC(init_ϵ, n_leapfrog, integrator, metric)
+function HMC(n_leapfrog; integrator = :leapfrog, metric = :diagonal)
+    if integrator isa Symbol
+        T = typeof(0.0) # current default float type
+    else
+        T = integrator_eltype(integrator)
+    end
+    return HMC{T}(n_leapfrog, integrator, metric)
 end
 
 #############
 ### HMCDA ###
 #############
 """
-    HMCDA(n_adapts::Int, δ::Real, λ::Real; ϵ::Real=0)
+    HMCDA(δ::Real, λ::Real; ϵ::Real=0, integrator = :leapfrog, metric = :diagonal)
 
 Hamiltonian Monte Carlo sampler with Dual Averaging algorithm.
 
@@ -130,7 +122,7 @@ $(FIELDS)
 # Usage:
 
 ```julia
-HMCDA(n_adapts=200, δ=0.65, λ=0.3)
+HMCDA(δ=0.65, λ=0.3)
 ```
 
 For more information, please view the following paper ([arXiv link](https://arxiv.org/abs/1111.4246)):
@@ -144,16 +136,14 @@ struct HMCDA{T<:Real} <: AbstractHMCSampler{T}
     δ::T
     "Target leapfrog length."
     λ::T
-    "Initial step size; 0 means automatically searching using a heuristic procedure."
-    init_ϵ::T
     "Choice of integrator, specified either using a `Symbol` or [`AbstractIntegrator`](@ref)"
     integrator::Union{Symbol,AbstractIntegrator}
-    "Choice of initial metric, specified using a `Symbol` or `AbstractMetric`. The metric type will be preserved during adaption."
+    "Choice of initial metric;  `Symbol` means it is automatically initialised. The metric type will be preserved during automatic initialisation and adaption."
     metric::Union{Symbol,AbstractMetric}
 end
 
 function HMCDA(δ, λ; init_ϵ = 0, integrator = :leapfrog, metric = :diagonal)
     δ, λ = promote(δ, λ)
     T = typeof(δ)
-    return HMCDA(δ, T(λ), T(init_ϵ), integrator, metric)
+    return HMCDA(δ, T(λ), integrator, metric)
 end

src/integrator.jl

@@ -70,6 +70,7 @@ struct Leapfrog{T<:AbstractScalarOrVec{<:AbstractFloat}} <: AbstractLeapfrog{T}
     ϵ::T
 end
 Base.show(io::IO, l::Leapfrog) = print(io, "Leapfrog(ϵ=$(round.(l.ϵ; sigdigits=3)))")
+integrator_eltype(i::AbstractLeapfrog{T}) where {T<:AbstractFloat} = T
 
 ### Jittering
 

test/abstractmcmc.jl

@@ -9,7 +9,7 @@ include("common.jl")
     θ_init = randn(rng, 2)
 
     nuts = NUTS(0.8)
-    hmc = HMC(0.05, 100)
+    hmc = HMC(100; integrator = Leapfrog(0.05))
     hmcda = HMCDA(0.8, 0.1)
 
     integrator = Leapfrog(1e-3)

test/constructors.jl

@@ -8,7 +8,7 @@ include("common.jl")
     @testset "$T" for T in [Float32, Float64]
         @testset "$(nameof(typeof(sampler)))" for (sampler, expected) in [
             (
-                HMC(T(0.1), 25),
+                HMC(25),
                 (
                     adaptor_type = NoAdaptation,
                     metric_type = DiagEuclideanMetric{T},
@@ -48,6 +48,22 @@ include("common.jl")
                     integrator_type = Leapfrog{T},
                 ),
             ),
+            (
+                NUTS(T(0.8); integrator = :jitteredleapfrog),
+                (
+                    adaptor_type = StanHMCAdaptor,
+                    metric_type = DiagEuclideanMetric{T},
+                    integrator_type = JitterdLeapfrog{T},
+                ),
+            ),
+            (
+                NUTS(T(0.8); integrator = :temperedleapfrog),
+                (
+                    adaptor_type = StanHMCAdaptor,
+                    metric_type = DiagEuclideanMetric{T},
+                    integrator_type = TemperedLeapfrog{T},
+                ),
+            ),
         ]
             # Make sure the sampler element type is preserved.
             @test AdvancedHMC.sampler_eltype(sampler) == T