156 lines
3.3 KiB
Go
156 lines
3.3 KiB
Go
/*
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Copyright © 2025 filifa
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package markov
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import (
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"errors"
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"math"
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"strconv"
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"gonum.org/v1/gonum/graph"
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"gonum.org/v1/gonum/graph/encoding"
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"gonum.org/v1/gonum/graph/multi"
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"gonum.org/v1/gonum/graph/simple"
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"gonum.org/v1/gonum/mat"
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)
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type AbsorbingMarkovChain struct {
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*multi.WeightedDirectedGraph
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}
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func NewAbsorbingMarkovChain() *AbsorbingMarkovChain {
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return &AbsorbingMarkovChain{WeightedDirectedGraph: multi.NewWeightedDirectedGraph()}
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}
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func (g *AbsorbingMarkovChain) IsValid() bool {
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for nodes := g.Nodes(); nodes.Next(); {
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u := nodes.Node()
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if g.outWeightSum(u) != 1 {
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return false
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}
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}
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return true
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}
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func (g *AbsorbingMarkovChain) outWeightSum(u graph.Node) float64 {
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sum := 0.0
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for nodes := g.From(u.ID()); nodes.Next(); {
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v := nodes.Node()
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e := g.WeightedEdge(u.ID(), v.ID())
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if e != nil {
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sum += e.Weight()
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}
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}
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return sum
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}
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func (g *AbsorbingMarkovChain) AbsorbingNodes() []graph.Node {
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absorbingNodes := make([]graph.Node, 0)
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for nodes := g.Nodes(); nodes.Next(); {
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u := nodes.Node()
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successors := g.From(u.ID())
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if successors.Len() != 1 {
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continue
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}
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successors.Next()
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v := successors.Node()
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if u == v {
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absorbingNodes = append(absorbingNodes, u)
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}
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}
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return absorbingNodes
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}
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func (g *AbsorbingMarkovChain) AdjacencyMatrix() mat.Matrix {
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adj := simple.NewDirectedMatrix(g.Nodes().Len(), 0, 0, 0)
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for edges := g.WeightedEdges(); edges.Next(); {
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e := edges.WeightedEdge()
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if e.From() == e.To() {
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continue
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}
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adj.SetWeightedEdge(e)
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}
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a := mat.DenseCopyOf(adj.Matrix())
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nodes := adj.Nodes()
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for i := 0; nodes.Next(); i++ {
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id := nodes.Node().ID()
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u := g.Node(id)
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e := g.WeightedEdge(u.ID(), u.ID())
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if e != nil {
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a.Set(i, i, e.Weight())
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}
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}
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return a
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}
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func (g *AbsorbingMarkovChain) NewEdge(from, to graph.Node) graph.Edge {
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e := g.WeightedDirectedGraph.NewWeightedLine(from, to, math.NaN()).(multi.WeightedLine)
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return &weightedEdge{WeightedLine: e}
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}
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func (g *AbsorbingMarkovChain) NewNode() graph.Node {
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return &node{Node: g.WeightedDirectedGraph.NewNode()}
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}
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func (g *AbsorbingMarkovChain) SetEdge(e graph.Edge) {
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g.WeightedDirectedGraph.SetWeightedLine(e.(*weightedEdge))
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}
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type weightedEdge struct {
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multi.WeightedLine
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}
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func (e *weightedEdge) ReversedEdge() graph.Edge {
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revLine := multi.WeightedLine{F: e.T, T: e.F, W: e.W}
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return &weightedEdge{WeightedLine: revLine}
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}
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func (e *weightedEdge) SetAttribute(attr encoding.Attribute) error {
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var err error
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switch attr.Key {
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case "weight":
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e.W, err = strconv.ParseFloat(attr.Value, 64)
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default:
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err = errors.New("unknown key" + attr.Key)
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}
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return err
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}
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type node struct {
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graph.Node
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dotID string
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}
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func (n *node) SetDOTID(id string) {
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n.dotID = id
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}
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func (n *node) DOTID() string {
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return n.dotID
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}
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