[Nonlinear] add amontoison's Forest type and remove DataStructures.jl

Project.toml

@@ -6,7 +6,6 @@ version = "1.46.0"
 BenchmarkTools = "6e4b80f9-dd63-53aa-95a3-0cdb28fa8baf"
 CodecBzip2 = "523fee87-0ab8-5b00-afb7-3ecf72e48cfd"
 CodecZlib = "944b1d66-785c-5afd-91f1-9de20f533193"
-DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 JSON3 = "0f8b85d8-7281-11e9-16c2-39a750bddbf1"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
@@ -23,7 +22,6 @@ Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 BenchmarkTools = "1"
 CodecBzip2 = "0.6, 0.7, 0.8"
 CodecZlib = "0.6, 0.7"
-DataStructures = "0.18, 0.19"
 ForwardDiff = "0.10, 1"
 JSON3 = "1"
 JSONSchema = "1"

src/FileFormats/MPS/MPS.jl

@@ -8,7 +8,7 @@ module MPS
 
 import ..FileFormats
 import MathOptInterface as MOI
-import DataStructures: OrderedDict
+import OrderedCollections: OrderedDict
 
 const IndicatorLessThanTrue{T} =
     MOI.Indicator{MOI.ACTIVATE_ON_ONE,MOI.LessThan{T}}

src/Nonlinear/ReverseAD/Coloring/Coloring.jl

@@ -6,8 +6,7 @@
 
 module Coloring
 
-import DataStructures
-
+include("IntDisjointSet.jl")
 include("topological_sort.jl")
 
 """
@@ -154,7 +153,7 @@ function _prevent_cycle(
     forbiddenColors,
     color,
 )
-    er = DataStructures.find_root!(S, e_idx2)
+    er = _find_root!(S, e_idx2)
     @inbounds first = firstVisitToTree[er]
     p = first.source # but this depends on the order?
     q = first.target
@@ -172,29 +171,18 @@ function _grow_star(v, w, e_idx, firstNeighbor, color, S)
     @inbounds if p != v
         firstNeighbor[color[w]] = _Edge(e_idx, v, w)
     else
-        union!(S, e_idx, e.index)
+        _root_union!(S, e_idx, e.index)
     end
     return
 end
 
-function _merge_trees(eg, eg1, S)
-    e1 = DataStructures.find_root!(S, eg)
-    e2 = DataStructures.find_root!(S, eg1)
-    if e1 != e2
-        union!(S, eg, eg1)
+function _merge_trees(S::_IntDisjointSet, eg::Int, eg1::Int)
+    if _find_root!(S, eg) != _find_root!(S, eg1)
+        _root_union!(S, eg, eg1)
     end
     return
 end
 
-# Work-around a deprecation in DataStructures@0.19
-function _IntDisjointSet(n)
-    @static if isdefined(DataStructures, :IntDisjointSet)
-        return DataStructures.IntDisjointSet(n)
-    else
-        return DataStructures.IntDisjointSets(n)                 # COV_EXCL_LINE
-    end
-end
-
 """
     acyclic_coloring(g::UndirectedGraph)
 
@@ -214,7 +202,6 @@ function acyclic_coloring(g::UndirectedGraph)
     firstNeighbor = _Edge[]
     firstVisitToTree = fill(_Edge(0, 0, 0), _num_edges(g))
     color = fill(0, _num_vertices(g))
-    # disjoint set forest of edges in the graph
     S = _IntDisjointSet(_num_edges(g))
     @inbounds for v in 1:_num_vertices(g)
         n_neighbor = _num_neighbors(v, g)
@@ -293,7 +280,7 @@ function acyclic_coloring(g::UndirectedGraph)
                     continue
                 end
                 if color[x] == color[v]
-                    _merge_trees(e_idx, e2_idx, S)
+                    _merge_trees(S, e_idx, e2_idx)
                 end
             end
         end

src/Nonlinear/ReverseAD/Coloring/IntDisjointSet.jl

@@ -0,0 +1,47 @@
+# Copyright (c) 2017: Miles Lubin and contributors
+# Copyright (c) 2017: Google Inc.
+# Copyright (c) 2024: Guillaume Dalle and Alexis Montoison
+#
+# Use of this source code is governed by an MIT-style license that can be found
+# in the LICENSE.md file or at https://opensource.org/licenses/MIT.
+
+# The code in this file was taken from
+# https://github.com/gdalle/SparseMatrixColorings.jl/blob/main/src/Forest.jl
+#
+# It was copied at the suggestion of Alexis in his JuMP-dev 2025 talk.
+#
+# @odow made minor changes to match MOI coding styles.
+#
+# x-ref https://github.com/gdalle/SparseMatrixColorings.jl/pull/190
+
+mutable struct _IntDisjointSet
+    # current number of distinct trees in the S
+    number_of_trees::Int
+    # vector storing the index of a parent in the tree for each edge, used in
+    # union-find operations
+    parents::Vector{Int}
+    # vector approximating the depth of each tree to optimize path compression
+    ranks::Vector{Int}
+
+    _IntDisjointSet(n::Integer) = new(n, collect(1:n), zeros(Int, n))
+end
+
+function _find_root!(S::_IntDisjointSet, x::Integer)
+    p = S.parents[x]
+    if S.parents[p] != p
+        S.parents[x] = p = _find_root!(S, p)
+    end
+    return p
+end
+
+function _root_union!(S::_IntDisjointSet, x::Int, y::Int)
+    rank1, rank2 = S.ranks[x], S.ranks[y]
+    if rank1 < rank2
+        x, y = y, x
+    elseif rank1 == rank2
+        S.ranks[x] += 1
+    end
+    S.parents[y] = x
+    S.number_of_trees -= 1
+    return
+end

test/FileFormats/MPS/MPS.jl

@@ -10,7 +10,7 @@ using Test
 
 import MathOptInterface as MOI
 import MathOptInterface.FileFormats: MPS
-import DataStructures: OrderedDict
+import OrderedCollections: OrderedDict
 
 function runtests()
     for name in names(@__MODULE__; all = true)

test/Nonlinear/ReverseAD.jl

@@ -11,9 +11,9 @@ import LinearAlgebra
 import MathOptInterface as MOI
 import SparseArrays
 
-const Nonlinear = MOI.Nonlinear
-const ReverseAD = Nonlinear.ReverseAD
-const Coloring = ReverseAD.Coloring
+import MathOptInterface.Nonlinear
+import MathOptInterface.Nonlinear.ReverseAD
+import MathOptInterface.Nonlinear.ReverseAD.Coloring
 
 function runtests()
     for name in names(@__MODULE__; all = true)
@@ -1421,6 +1421,33 @@ function test_hessian_reinterpret_unsafe()
     return
 end
 
+function test_IntDisjointSet()
+    for case in [
+        [(1, 2) => [1, 1, 3], (1, 3) => [1, 1, 1]],
+        [(1, 2) => [1, 1, 3], (3, 1) => [1, 1, 1]],
+        [(2, 1) => [2, 2, 3], (1, 3) => [2, 2, 2]],
+        [(2, 1) => [2, 2, 3], (3, 1) => [3, 2, 3]],
+        [(1, 3) => [1, 2, 1], (2, 3) => [1, 2, 2]],
+        [(1, 3) => [1, 2, 1], (3, 2) => [1, 1, 1]],
+        [(3, 1) => [3, 2, 3], (2, 3) => [3, 3, 3]],
+        [(3, 1) => [3, 2, 3], (3, 2) => [3, 3, 3]],
+        [(2, 3) => [1, 2, 2], (1, 3) => [1, 2, 1]],
+        [(2, 3) => [1, 2, 2], (3, 1) => [2, 2, 2]],
+        [(3, 2) => [1, 3, 3], (1, 3) => [3, 3, 3]],
+        [(3, 2) => [1, 3, 3], (3, 1) => [3, 3, 3]],
+    ]
+        S = Coloring._IntDisjointSet(3)
+        @test Coloring._find_root!.((S,), [1, 2, 3]) == [1, 2, 3]
+        @test S.number_of_trees == 3
+        for (i, (union, result)) in enumerate(case)
+            Coloring._root_union!(S, union[1], union[2])
+            @test Coloring._find_root!.((S,), [1, 2, 3]) == result
+            @test S.number_of_trees == 3 - i
+        end
+    end
+    return
+end
+
 end  # module
 
 TestReverseAD.runtests()