added erdos renyi ensemble

src/MultilevelChainSampler.jl

@@ -7,17 +7,22 @@ using Distributions
 using Random, StatsBase
 using Primes, HaltonSequences
 
+using Graphs
+
 import Base: rand, length, size
 import Distributions: logpdf
 import StatsBase: sample
 
+export logdensity
 export LogDensity, SampledLogDensity
 export MultilevelLogDensity, MultilevelSampledLogDensity
-export logdensity
-export propose, logpratio
-export MetropolisHastings, ChristenFox
+
+export propose
 export RandomWalk, CyclicWalk
+export ErdosRenyi
+
 export sample
+export MetropolisHastings, ChristenFox
 export DefaultChains
 
 include("models/all.jl")

src/proposals/networks.jl

+abstract type NetworkEnsemble <: AbstractProposal end
+
+struct ErdosRenyi <: NetworkEnsemble
+    n::Int64
+    p::Float64
+    s::Int64
+end
+ErdosRenyi(n::Int64) = ErdosRenyi(n, log(n)/n * (1 + exp(-rand())))
+ErdosRenyi(n::Int64, p::AbstractFloat) = ErdosRenyi(n, p, ceil(Int, log(n)))
+ErdosRenyi(n::Int64, m::Int64, s::Int64=ceil(Int, log(n))) = ErdosRenyi(n, m/(n*(n-1)/2), s)
+
+Base.rand(rng::AbstractRNG, e::ErdosRenyi) = erdos_renyi(e.n, e.p; rng)
+
+function propose(rng::AbstractRNG, e::ErdosRenyi, G::Graph)
+    G = copy(G)
+    for t = 1:e.s
+
+        # Choose a pair
+        u = rand(rng, 1:nv(G))
+        v = rand(rng, 1:nv(G)-1)
+        if (v>=u) v+=1 end
+
+        # Resample edge 
+        if has_edge(G, u, v)
+            if rand(rng) < 1 - e.p
+                rem_edge!(G, u, v)
+            end
+        else
+            if rand(rng) < e.p
+                add_edge!(G, u, v)
+            end
+        end
+    end
+    return G
+end
\ No newline at end of file

test/run_tests.jl

@@ -4,10 +4,10 @@ using AbstractMCMC: MCMCSerial #, MCMCThreads, MCMCDistributed
 using CairoMakie
 
 using Revise
-using Pkg; Pkg.activate(".")
+#using Pkg; Pkg.activate(".")
 using MultilevelChainSampler
 
-
+#=
 function analyse(chains)
 
     t = TruncatedNormal(0, 1, -1, 1)
@@ -59,3 +59,4 @@ begin # Sample Based Energy Function
 
     analyse(chains)
 end
+=#
\ No newline at end of file

test/test_proposals.jl

+
+using Random, StatsBase, Distributions
+using Graphs
+using AbstractMCMC: MCMCSerial #, MCMCThreads, MCMCDistributed
+using CairoMakie
+
+using Test
+using Revise
+using MultilevelChainSampler
+
+rng = Random.default_rng()
+function chain(g) 
+    x = [ rand(g) ]
+    for i=1:1000
+        y = MultilevelChainSampler.propose(rng, g, x[end])
+        push!(x, y)
+    end
+    return x
+end
+    
+w = CyclicWalk(-1,1,.5)
+x = chain(w)
+@test abs( mean(x) ) <  0.1
+@test abs( std(x) - .5) < 0.1
+
+er = ErdosRenyi(1000)
+x = chain(er)
+c = is_connected.(x)
+@test mean(c) > .5
+k = mean.(degree.(x))
+@test abs( mean(k) - er.n * er.p ) < 1