Add weights(::AbstractITensorNetwork), new graph partitioning inter…

…face

docs/make.jl

@@ -1,7 +1,9 @@
 using ITensorNetworks
 using Documenter
 
-DocMeta.setdocmeta!(ITensorNetworks, :DocTestSetup, :(using ITensorNetworks); recursive=true)
+DocMeta.setdocmeta!(
+  ITensorNetworks, :DocTestSetup, :(using ITensorNetworks); recursive=true
+)
 
 makedocs(;
   modules=[ITensorNetworks],

examples/README.jl

@@ -61,4 +61,8 @@ Z̃ = contract(Z, (1, 1) => (2, 1));
 #+ eval=false
 
 using ITensorNetworks, Weave
-weave(joinpath(pkgdir(ITensorNetworks), "examples", "README.jl"); doctype="github", out_path=pkgdir(ITensorNetworks))
+weave(
+  joinpath(pkgdir(ITensorNetworks), "examples", "README.jl");
+  doctype="github",
+  out_path=pkgdir(ITensorNetworks),
+)

examples/belief_propagation/bpexample.jl

@@ -3,10 +3,7 @@ using ITensors
 using Metis
 using ITensorNetworks
 
-using ITensorNetworks:
-  construct_initial_mts,
-  update_all_mts,
-  get_single_site_expec
+using ITensorNetworks: construct_initial_mts, update_all_mts, get_single_site_expec
 
 n = 4
 dims = (n, n)

examples/boundary.jl

@@ -0,0 +1,20 @@
+using NamedGraphs
+using ITensors
+using ITensorNetworks
+using ITensorUnicodePlots
+using Metis
+
+tn = ITensorNetwork(named_grid((6, 3)); link_space=4)
+
+@visualize tn
+
+g = subgraph_vertices(tn; nvertices_per_partition=2)
+sub_vs_1, sub_vs_2 = g[1], g[2]
+
+@show (1, 1) ∈ sub_vs_1
+@show (6, 3) ∈ sub_vs_2
+
+@show boundary_edges(tn, sub_vs_1)
+@show boundary_vertices(tn, sub_vs_1)
+@show inner_boundary_vertices(tn, sub_vs_1)
+@show outer_boundary_vertices(tn, sub_vs_1)

examples/distances.jl

@@ -0,0 +1,17 @@
+using NamedGraphs
+using ITensors
+using ITensorNetworks
+using ITensorUnicodePlots
+
+g = named_grid((3, 5))
+s = siteinds("S=1/2", g)
+ψ = ITensorNetwork(s; link_space=4)
+@visualize ψ
+@show center(ψ)
+@show periphery(ψ)
+t = dijkstra_tree(ψ, only(center(ψ)))
+@visualize t
+@show a_star(ψ, (2, 1), (2, 5))
+@show mincut_partitions(ψ)
+@show mincut_partitions(ψ, (1, 1), (3, 5))
+@show subgraph_vertices(ψ; npartitions=2)

examples/group_partition.jl

@@ -0,0 +1,17 @@
+using ITensors
+using Graphs
+using NamedGraphs
+using ITensorNetworks
+using SplitApplyCombine
+using Metis
+
+s = siteinds("S=1/2", named_grid(8))
+tn = ITensorNetwork(s; link_space=2)
+Z = prime(tn; sites=[]) ⊗ tn
+vertex_groups = group(v -> v[1], vertices(Z))
+# Create two layers of partitioning
+Z_p = partition(partition(Z, vertex_groups); nvertices_per_partition=2)
+# Flatten the partitioned partitions
+Z_verts = [
+  reduce(vcat, (vertices(Z_p[vp][v]) for v in vertices(Z_p[vp]))) for vp in vertices(Z_p)
+]

examples/mincut.jl

@@ -0,0 +1,55 @@
+using NamedGraphs
+using ITensors
+using ITensorNetworks
+using ITensorUnicodePlots
+
+g = named_grid(5)
+s = siteinds("S=1/2", g)
+
+ψ = ITensorNetwork(s; link_space=10)
+
+# ρ = flatten_networks(dag(ψ), ψ')
+
+# Or:
+
+ss = ∪(dag(s), s'; merge_data=union)
+ρ = ITensorNetwork(ss; link_space=2)
+
+tn = ⊗(ρ', ρ, ψ)
+tn_flattened = flatten_networks(ρ', ρ, ψ)
+# tn = ρ' ⊗ ρ ⊗ ψ
+@visualize tn
+
+@show center(tn)
+
+v = first(center(tn))
+
+dijk_parents = dijkstra_parents(tn, v)
+dijk_mst = dijkstra_mst(tn, v)
+dijk_tree = dijkstra_tree(tn, v)
+
+bfs_tree_tn = bfs_tree(tn, v)
+
+@show eccentricity(tn, v)
+@show radius(tn)
+@show radius(tn)
+@show diameter(tn)
+@show periphery(tn)
+
+s = dijk_tree
+t = bfs_tree_tn
+@visualize s
+@visualize t
+
+v1 = first(periphery(tn))
+nds = neighborhood_dists(tn, v1, nv(tn))
+d_and_i = findmax(vd -> vd[2], nds)
+v2 = nds[d_and_i[2]][1]
+@show v1, v2
+p1, p2 = mincut_partitions(tn, v1, v2)
+@show p1
+@show p2
+
+display(adjacency_matrix(tn_flattened))
+tn_flattened_p = symrcm_permute(tn_flattened)
+display(adjacency_matrix(tn_flattened_p))

examples/partition/kahypar_vs_metis.jl

@@ -6,7 +6,39 @@ using ITensorNetworks
 g = grid((16,))
 npartitions = 4
 
-kahypar_partitions = partition(g, npartitions; backend="KaHyPar")
-metis_partitions = partition(g, npartitions; backend="Metis")
-@show kahypar_partitions, length(unique(kahypar_partitions))
-@show metis_partitions, length(unique(metis_partitions))
+kahypar_partitions = subgraph_vertices(g; npartitions, backend="KaHyPar")
+metis_partitions = subgraph_vertices(g; npartitions, backend="Metis")
+@show kahypar_partitions, length(kahypar_partitions)
+@show metis_partitions, length(metis_partitions)
+
+g_parts = partition(g; npartitions)
+@show nv(g_parts) == 4
+@show nv(g_parts[1]) == 4
+@show nv(g_parts[2]) == 4
+@show nv(g_parts[3]) == 4
+@show nv(g_parts[4]) == 4
+@show issetequal(metis_partitions[2], vertices(g_parts[2]))
+
+using ITensorNetworks
+tn = ITensorNetwork(named_grid((4, 2)); link_space=3);
+
+# subgraph_vertices
+tn_sv = subgraph_vertices(tn; npartitions=2) # Same as `partition_vertices(tn; nvertices_per_partition=4)`
+
+# partition_vertices
+tn_pv = partition_vertices(tn; npartitions=2);
+typeof(tn_pv)
+tn_pv[1]
+edges(tn_pv)
+tn_pv[1 => 2]
+
+# subgraphs
+tn_sg = subgraphs(tn; npartitions=2);
+typeof(tn_sg)
+tn_sg[1]
+
+# partition
+tn_pg = partition(tn; npartitions=2);
+typeof(tn_pg)
+tn_pg[1]
+tn_pg[1 => 2][:edges]

examples/partition/partitioning.jl

@@ -24,7 +24,7 @@ neighbor_edges = [v => nv for nv in neighbors(ψ, v)]
 @show [e => linkinds(ψ, e) for e in neighbor_edges]
 
 npartitions = 4
-partitions = partition(ψ, npartitions)
+partitions = partition(ψ; npartitions)
 
 @show partitions
 

examples/steiner_tree.jl

@@ -0,0 +1,16 @@
+using NamedGraphs
+using ITensors
+using ITensorNetworks
+using ITensorUnicodePlots
+
+tn = ITensorNetwork(named_grid((3, 5)); link_space=4)
+
+@visualize tn
+
+terminal_vertices = [(1, 2), (1, 4), (3, 4)]
+st = steiner_tree(tn, terminal_vertices)
+
+@show has_edge(st, (1, 2) => (1, 3))
+@show has_edge(st, (1, 3) => (1, 4))
+@show has_edge(st, (1, 4) => (2, 4))
+@show has_edge(st, (2, 4) => (3, 4))

examples/ttns/ttn_type.jl

@@ -101,7 +101,9 @@ for e in post_order_dfs_edges(ψ_ortho, root_vertex)
 end
 
 @show √(
-  contract(norm_sqr_network(ψ_ortho); sequence=contraction_sequence(norm_sqr_network(ψ_ortho)))[]
+  contract(
+    norm_sqr_network(ψ_ortho); sequence=contraction_sequence(norm_sqr_network(ψ_ortho))
+  )[],
 )
 @show √(contract(norm_sqr_network(ψ); sequence=contraction_sequence(norm_sqr_network(ψ)))[])
 @show norm(ψ_ortho[root_vertex])

src/ITensorNetworks.jl

@@ -17,15 +17,26 @@ using Suppressor
 # TODO: export from ITensors
 using ITensors: commontags, @Algorithm_str, Algorithm
 using Graphs: AbstractEdge, AbstractGraph, Graph, add_edge!
+using Graphs.SimpleGraphs # AbstractSimpleGraph
 using NamedGraphs:
   AbstractNamedGraph,
   parent_graph,
   vertex_to_parent_vertex,
+  parent_vertices_to_vertices,
   not_implemented
-using DataGraphs: vertex_data_type
+using DataGraphs: edge_data_type, vertex_data_type
 
 include("imports.jl")
 
+# TODO: Move to `DataGraphs.jl`
+edge_data_type(::AbstractNamedGraph) = Any
+isassigned(::AbstractNamedGraph, ::Any) = false
+function iterate(::AbstractDataGraph)
+  return error(
+    "Iterating data graphs is not yet defined. We may define it in the future as iterating through the vertex and edge data.",
+  )
+end
+
 include("utils.jl")
 include("visualize.jl")
 include("graphs.jl")
@@ -47,7 +58,6 @@ include("itensornetwork.jl")
 include("specialitensornetworks.jl")
 include("renameitensornetwork.jl")
 include("boundarymps.jl")
-include("subgraphs.jl")
 include("beliefpropagation.jl")
 include(joinpath("treetensornetwork", "treetensornetwork.jl"))
 

src/abstractindsnetwork.jl

@@ -1,5 +1,4 @@
-abstract type AbstractIndsNetwork{V,I} <:
-              AbstractDataGraph{V,Vector{I},Vector{I}} end
+abstract type AbstractIndsNetwork{V,I} <: AbstractDataGraph{V,Vector{I},Vector{I}} end
 
 # Field access
 data_graph(graph::AbstractIndsNetwork) = not_implemented()
@@ -11,6 +10,9 @@ is_directed(::Type{<:AbstractIndsNetwork}) = false
 vertex_data(graph::AbstractIndsNetwork, args...) = vertex_data(data_graph(graph), args...)
 edge_data(graph::AbstractIndsNetwork, args...) = edge_data(data_graph(graph), args...)
 
+# TODO: Define a generic fallback for `AbstractDataGraph`?
+edge_data_type(::Type{<:AbstractIndsNetwork{V,I}}) where {V,I} = Vector{I}
+
 # 
 # Index access
 # 
@@ -27,18 +29,11 @@ function uniqueinds(is::AbstractIndsNetwork, edge::Pair)
   return uniqueinds(is, edgetype(is)(edge))
 end
 
-function union(
-  tn1::AbstractIndsNetwork,
-  tn2::AbstractIndsNetwork;
-  kwargs...,
-)
-  return IndsNetwork(union(data_graph(tn1), data_graph(tn2)); kwargs...)
+function union(tn1::AbstractIndsNetwork, tn2::AbstractIndsNetwork; kwargs...)
+  return IndsNetwork(union(data_graph(tn1), data_graph(tn2); kwargs...))
 end
 
-function rename_vertices(
-  f::Function,
-  tn::AbstractIndsNetwork,
-)
+function rename_vertices(f::Function, tn::AbstractIndsNetwork)
   return IndsNetwork(rename_vertices(f, data_graph(tn)))
 end