75 lines
2.1 KiB
Go
75 lines
2.1 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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"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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)
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// Node is a DOT-aware graph.Node.
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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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// SetDOTID sets the node's DOT ID. It enables storing the node name read from
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// a DOT file.
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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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// DOTID returns the node's DOT ID.
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func (n *Node) DOTID() string {
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return n.dotID
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}
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// weightedEdge is a DOT-aware multi.WeightedLine. By being a
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// multi.WeightedLine, it allows for self-loops, which are important for
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// absorbing Markov chains.
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// TODO: this is a little confusing, maybe just have checks in the code that
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// there's only one line in each edge?
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type weightedEdge struct {
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multi.WeightedLine
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}
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// ReversedEdge returns a new weightedEdge with the same weight, but the
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// direction reversed. It exists mainly to satisfy the graph.Edge interface.
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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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// SetAttribute enables storing the weight read from a DOT file. It errors if
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// an attribute is read that can't be stored in a weightedEdge.
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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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