Fix A* implementation

.gitignore

@@ -7,4 +7,4 @@ docs/site/
 benchmark/.results/*
 benchmark/.tune.jld
 *.cov
-Manifest.toml
+/Manifest.toml

docs/Manifest.toml

@@ -0,0 +1,238 @@
+# This file is machine-generated - editing it directly is not advised
+
+julia_version = "1.7.2"
+manifest_format = "2.0"
+
+[[deps.ArgTools]]
+uuid = "0dad84c5-d112-42e6-8d28-ef12dabb789f"
+
+[[deps.ArnoldiMethod]]
+deps = ["LinearAlgebra", "Random", "StaticArrays"]
+git-tree-sha1 = "62e51b39331de8911e4a7ff6f5aaf38a5f4cc0ae"
+uuid = "ec485272-7323-5ecc-a04f-4719b315124d"
+version = "0.2.0"
+
+[[deps.Artifacts]]
+uuid = "56f22d72-fd6d-98f1-02f0-08ddc0907c33"
+
+[[deps.Base64]]
+uuid = "2a0f44e3-6c83-55bd-87e4-b1978d98bd5f"
+
+[[deps.Compat]]
+deps = ["Base64", "Dates", "DelimitedFiles", "Distributed", "InteractiveUtils", "LibGit2", "Libdl", "LinearAlgebra", "Markdown", "Mmap", "Pkg", "Printf", "REPL", "Random", "SHA", "Serialization", "SharedArrays", "Sockets", "SparseArrays", "Statistics", "Test", "UUIDs", "Unicode"]
+git-tree-sha1 = "b153278a25dd42c65abbf4e62344f9d22e59191b"
+uuid = "34da2185-b29b-5c13-b0c7-acf172513d20"
+version = "3.43.0"
+
+[[deps.CompilerSupportLibraries_jll]]
+deps = ["Artifacts", "Libdl"]
+uuid = "e66e0078-7015-5450-92f7-15fbd957f2ae"
+
+[[deps.DataStructures]]
+deps = ["Compat", "InteractiveUtils", "OrderedCollections"]
+git-tree-sha1 = "cc1a8e22627f33c789ab60b36a9132ac050bbf75"
+uuid = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
+version = "0.18.12"
+
+[[deps.Dates]]
+deps = ["Printf"]
+uuid = "ade2ca70-3891-5945-98fb-dc099432e06a"
+
+[[deps.DelimitedFiles]]
+deps = ["Mmap"]
+uuid = "8bb1440f-4735-579b-a4ab-409b98df4dab"
+
+[[deps.Distributed]]
+deps = ["Random", "Serialization", "Sockets"]
+uuid = "8ba89e20-285c-5b6f-9357-94700520ee1b"
+
+[[deps.DocStringExtensions]]
+deps = ["LibGit2"]
+git-tree-sha1 = "b19534d1895d702889b219c382a6e18010797f0b"
+uuid = "ffbed154-4ef7-542d-bbb7-c09d3a79fcae"
+version = "0.8.6"
+
+[[deps.Documenter]]
+deps = ["Base64", "Dates", "DocStringExtensions", "IOCapture", "InteractiveUtils", "JSON", "LibGit2", "Logging", "Markdown", "REPL", "Test", "Unicode"]
+git-tree-sha1 = "3ebb967819b284dc1e3c0422229b58a40a255649"
+uuid = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
+version = "0.26.3"
+
+[[deps.Downloads]]
+deps = ["ArgTools", "LibCURL", "NetworkOptions"]
+uuid = "f43a241f-c20a-4ad4-852c-f6b1247861c6"
+
+[[deps.Graphs]]
+deps = ["ArnoldiMethod", "Compat", "DataStructures", "Distributed", "Inflate", "LinearAlgebra", "Random", "SharedArrays", "SimpleTraits", "SparseArrays", "Statistics"]
+path = ".."
+uuid = "86223c79-3864-5bf0-83f7-82e725a168b6"
+version = "1.6.0"
+
+[[deps.IOCapture]]
+deps = ["Logging"]
+git-tree-sha1 = "377252859f740c217b936cebcd918a44f9b53b59"
+uuid = "b5f81e59-6552-4d32-b1f0-c071b021bf89"
+version = "0.1.1"
+
+[[deps.Inflate]]
+git-tree-sha1 = "f5fc07d4e706b84f72d54eedcc1c13d92fb0871c"
+uuid = "d25df0c9-e2be-5dd7-82c8-3ad0b3e990b9"
+version = "0.1.2"
+
+[[deps.InteractiveUtils]]
+deps = ["Markdown"]
+uuid = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
+
+[[deps.JSON]]
+deps = ["Dates", "Mmap", "Parsers", "Unicode"]
+git-tree-sha1 = "3c837543ddb02250ef42f4738347454f95079d4e"
+uuid = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
+version = "0.21.3"
+
+[[deps.LibCURL]]
+deps = ["LibCURL_jll", "MozillaCACerts_jll"]
+uuid = "b27032c2-a3e7-50c8-80cd-2d36dbcbfd21"
+
+[[deps.LibCURL_jll]]
+deps = ["Artifacts", "LibSSH2_jll", "Libdl", "MbedTLS_jll", "Zlib_jll", "nghttp2_jll"]
+uuid = "deac9b47-8bc7-5906-a0fe-35ac56dc84c0"
+
+[[deps.LibGit2]]
+deps = ["Base64", "NetworkOptions", "Printf", "SHA"]
+uuid = "76f85450-5226-5b5a-8eaa-529ad045b433"
+
+[[deps.LibSSH2_jll]]
+deps = ["Artifacts", "Libdl", "MbedTLS_jll"]
+uuid = "29816b5a-b9ab-546f-933c-edad1886dfa8"
+
+[[deps.Libdl]]
+uuid = "8f399da3-3557-5675-b5ff-fb832c97cbdb"
+
+[[deps.LinearAlgebra]]
+deps = ["Libdl", "libblastrampoline_jll"]
+uuid = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+
+[[deps.Logging]]
+uuid = "56ddb016-857b-54e1-b83d-db4d58db5568"
+
+[[deps.MacroTools]]
+deps = ["Markdown", "Random"]
+git-tree-sha1 = "3d3e902b31198a27340d0bf00d6ac452866021cf"
+uuid = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
+version = "0.5.9"
+
+[[deps.Markdown]]
+deps = ["Base64"]
+uuid = "d6f4376e-aef5-505a-96c1-9c027394607a"
+
+[[deps.MbedTLS_jll]]
+deps = ["Artifacts", "Libdl"]
+uuid = "c8ffd9c3-330d-5841-b78e-0817d7145fa1"
+
+[[deps.Mmap]]
+uuid = "a63ad114-7e13-5084-954f-fe012c677804"
+
+[[deps.MozillaCACerts_jll]]
+uuid = "14a3606d-f60d-562e-9121-12d972cd8159"
+
+[[deps.NetworkOptions]]
+uuid = "ca575930-c2e3-43a9-ace4-1e988b2c1908"
+
+[[deps.OpenBLAS_jll]]
+deps = ["Artifacts", "CompilerSupportLibraries_jll", "Libdl"]
+uuid = "4536629a-c528-5b80-bd46-f80d51c5b363"
+
+[[deps.OrderedCollections]]
+git-tree-sha1 = "85f8e6578bf1f9ee0d11e7bb1b1456435479d47c"
+uuid = "bac558e1-5e72-5ebc-8fee-abe8a469f55d"
+version = "1.4.1"
+
+[[deps.Parsers]]
+deps = ["Dates"]
+git-tree-sha1 = "1285416549ccfcdf0c50d4997a94331e88d68413"
+uuid = "69de0a69-1ddd-5017-9359-2bf0b02dc9f0"
+version = "2.3.1"
+
+[[deps.Pkg]]
+deps = ["Artifacts", "Dates", "Downloads", "LibGit2", "Libdl", "Logging", "Markdown", "Printf", "REPL", "Random", "SHA", "Serialization", "TOML", "Tar", "UUIDs", "p7zip_jll"]
+uuid = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
+
+[[deps.Printf]]
+deps = ["Unicode"]
+uuid = "de0858da-6303-5e67-8744-51eddeeeb8d7"
+
+[[deps.REPL]]
+deps = ["InteractiveUtils", "Markdown", "Sockets", "Unicode"]
+uuid = "3fa0cd96-eef1-5676-8a61-b3b8758bbffb"
+
+[[deps.Random]]
+deps = ["SHA", "Serialization"]
+uuid = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
+
+[[deps.SHA]]
+uuid = "ea8e919c-243c-51af-8825-aaa63cd721ce"
+
+[[deps.Serialization]]
+uuid = "9e88b42a-f829-5b0c-bbe9-9e923198166b"
+
+[[deps.SharedArrays]]
+deps = ["Distributed", "Mmap", "Random", "Serialization"]
+uuid = "1a1011a3-84de-559e-8e89-a11a2f7dc383"
+
+[[deps.SimpleTraits]]
+deps = ["InteractiveUtils", "MacroTools"]
+git-tree-sha1 = "5d7e3f4e11935503d3ecaf7186eac40602e7d231"
+uuid = "699a6c99-e7fa-54fc-8d76-47d257e15c1d"
+version = "0.9.4"
+
+[[deps.Sockets]]
+uuid = "6462fe0b-24de-5631-8697-dd941f90decc"
+
+[[deps.SparseArrays]]
+deps = ["LinearAlgebra", "Random"]
+uuid = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
+
+[[deps.StaticArrays]]
+deps = ["LinearAlgebra", "Random", "Statistics"]
+git-tree-sha1 = "cd56bf18ed715e8b09f06ef8c6b781e6cdc49911"
+uuid = "90137ffa-7385-5640-81b9-e52037218182"
+version = "1.4.4"
+
+[[deps.Statistics]]
+deps = ["LinearAlgebra", "SparseArrays"]
+uuid = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
+
+[[deps.TOML]]
+deps = ["Dates"]
+uuid = "fa267f1f-6049-4f14-aa54-33bafae1ed76"
+
+[[deps.Tar]]
+deps = ["ArgTools", "SHA"]
+uuid = "a4e569a6-e804-4fa4-b0f3-eef7a1d5b13e"
+
+[[deps.Test]]
+deps = ["InteractiveUtils", "Logging", "Random", "Serialization"]
+uuid = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+
+[[deps.UUIDs]]
+deps = ["Random", "SHA"]
+uuid = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
+
+[[deps.Unicode]]
+uuid = "4ec0a83e-493e-50e2-b9ac-8f72acf5a8f5"
+
+[[deps.Zlib_jll]]
+deps = ["Libdl"]
+uuid = "83775a58-1f1d-513f-b197-d71354ab007a"
+
+[[deps.libblastrampoline_jll]]
+deps = ["Artifacts", "Libdl", "OpenBLAS_jll"]
+uuid = "8e850b90-86db-534c-a0d3-1478176c7d93"
+
+[[deps.nghttp2_jll]]
+deps = ["Artifacts", "Libdl"]
+uuid = "8e850ede-7688-5339-a07c-302acd2aaf8d"
+
+[[deps.p7zip_jll]]
+deps = ["Artifacts", "Libdl"]
+uuid = "3f19e933-33d8-53b3-aaab-bd5110c3b7a0"

docs/Project.toml

@@ -1,5 +1,6 @@
 [deps]
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
+Graphs = "86223c79-3864-5bf0-83f7-82e725a168b6"
 
 [compat]
 Documenter = "~0.26.2"

src/shortestpaths/astar.jl

@@ -6,12 +6,11 @@
 function reconstruct_path!(total_path, # a vector to be filled with the shortest path
     came_from, # a vector holding the parent of each node in the A* exploration
     end_idx, # the end vertex
-    g) # the graph
-
-    E = edgetype(g)
+    g,  # the graph
+    edgetype_to_return::Type{E}=edgetype(g)) where {E<:AbstractEdge}
     curr_idx = end_idx
     while came_from[curr_idx] != curr_idx
-        pushfirst!(total_path, E(came_from[curr_idx], curr_idx))
+        pushfirst!(total_path, edgetype_to_return(came_from[curr_idx], curr_idx))
         curr_idx = came_from[curr_idx]
     end
 end
@@ -21,19 +20,17 @@ function a_star_impl!(g, # the graph
     open_set, # an initialized heap containing the active vertices
     closed_set, # an (initialized) color-map to indicate status of vertices
     g_score, # a vector holding g scores for each node
-    f_score, # a vector holding f scores for each node
     came_from, # a vector holding the parent of each node in the A* exploration
     distmx,
-    heuristic)
-
-    E = edgetype(g)
-    total_path = Vector{E}()
+    heuristic,
+    edgetype_to_return::Type{E}) where {E<:AbstractEdge}
+    total_path = Vector{edgetype_to_return}()
 
     @inbounds while !isempty(open_set)
         current = dequeue!(open_set)
 
         if current == goal
-            reconstruct_path!(total_path, came_from, current, g)
+            reconstruct_path!(total_path, came_from, current, g, edgetype_to_return)
             return total_path
         end
 
@@ -56,38 +53,47 @@ function a_star_impl!(g, # the graph
 end
 
 """
-    a_star(g, s, t[, distmx][, heuristic])
+    a_star(g, s, t[, distmx][, heuristic][, edgetype_to_return])
+
+Compute a shortest path using the [A* search algorithm](http://en.wikipedia.org/wiki/A%2A_search_algorithm).
 
-Return a vector of edges comprising the shortest path between vertices `s` and `t`
-using the [A* search algorithm](http://en.wikipedia.org/wiki/A%2A_search_algorithm).
-An optional heuristic function and edge distance matrix may be supplied. If missing,
-the distance matrix is set to [`Graphs.DefaultDistance`](@ref) and the heuristic is set to
-`n -> 0`.
+# Arguments
+- `g::AbstractGraph`: the graph
+- `s::Integer`: the source vertex
+- `t::Integer`: the target vertex
+- `distmx::AbstractMatrix`: an optional (possibly sparse) `n × n` matrix of edge weights. It is set to `weights(g)` by default (which itself falls back on [`Graphs.DefaultDistance`](@ref)).
+- `heuristic::Function`: an optional function mapping each vertex to a lower estimate of the remaining distance from `v` to `t`. It is set to `v -> 0` by default (which corresponds to Dijkstra's algorithm)
+- `edgetype_to_return::Type{E}`: the eltype `E<:AbstractEdge` of the vector of edges returned. It is set to `edgetype(g)` by default. Note that the two-argument constructor `E(u, v)` must be defined, even for weighted edges: if it isn't, consider using `E = Graphs.SimpleEdge`.
 """
 function a_star(g::AbstractGraph{U},  # the g
     s::Integer,                       # the start vertex
     t::Integer,                       # the end vertex
     distmx::AbstractMatrix{T}=weights(g),
-    heuristic::Function=n -> zero(T)) where {T, U}
-
-    E = Edge{eltype(g)}
-
+    heuristic::Function=n -> zero(T),
+    edgetype_to_return::Type{E}=edgetype(g)) where {T, U, E<:AbstractEdge}
     # if we do checkbounds here, we can use @inbounds in a_star_impl!
     checkbounds(distmx, Base.OneTo(nv(g)), Base.OneTo(nv(g)))
 
-    open_set = PriorityQueue{Integer, T}()
+    open_set = PriorityQueue{U, T}()
     enqueue!(open_set, s, 0)
 
     closed_set = zeros(Bool, nv(g))
 
     g_score = fill(Inf, nv(g))
     g_score[s] = 0
 
-    f_score = fill(Inf, nv(g))
-    f_score[s] = heuristic(s)
-
     came_from = fill(-one(s), nv(g))
     came_from[s] = s
 
-    a_star_impl!(g, t, open_set, closed_set, g_score, f_score, came_from, distmx, heuristic)
+    a_star_impl!(
+        g,
+        t,
+        open_set,
+        closed_set,
+        g_score,
+        came_from,
+        distmx,
+        heuristic,
+        edgetype_to_return
+    )
 end

test/shortestpaths/astar.jl

@@ -15,4 +15,11 @@
     g = complete_graph(4)
     w = float([1 1 1 4; 1 1 1 1; 1 1 1 1; 4 1 1 1])
     @test length(a_star(g, 1, 4, w)) == 2
+
+    # test for #120
+    struct MyFavoriteEdgeType <: AbstractEdge{Int}
+        s::Int
+        d::Int
+    end
+    @test eltype(a_star(g, 1, 4, w, n -> 0, MyFavoriteEdgeType)) == MyFavoriteEdgeType
 end