From 129a22cfcc7651daa4b11ed52e7870249f6373a5 Mon Sep 17 00:00:00 2001
From: Patrick Simianer <p@simianer.de>
Date: Tue, 16 Sep 2014 10:23:14 +0100
Subject: spring cleaning

---
 prototype/hypergraph.rb | 219 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 219 insertions(+)
 create mode 100644 prototype/hypergraph.rb

(limited to 'prototype/hypergraph.rb')

diff --git a/prototype/hypergraph.rb b/prototype/hypergraph.rb
new file mode 100644
index 0000000..d43d5ee
--- /dev/null
+++ b/prototype/hypergraph.rb
@@ -0,0 +1,219 @@
+require 'zipf'
+require_relative 'grammar'
+
+module HG
+
+class HG::Node
+  attr_accessor :id, :symbol, :left, :right, :outgoing, :incoming, :score
+
+  def initialize id=nil, symbol='', span=[-1,-1], outgoing=[], incoming=[], score=nil
+    @id       = id
+    @symbol   = symbol
+    @left     = span[0]
+    @right    = span[1]
+    @outgoing = outgoing
+    @incoming = incoming
+    @score    = score
+  end
+
+  def to_s
+    "Node<id=#{@id}, symbol='#{symbol}', span=(#{@left},#{@right}), outgoing:#{@outgoing.size}, incoming:#{@incoming.size}>"
+  end
+end
+
+class HG::Hypergraph
+  attr_accessor :nodes, :edges, :nodes_by_id
+
+  def initialize nodes=[], edges=[], nodes_by_id={}
+    @nodes       = nodes
+    @edges       = edges
+    @nodes_by_id = nodes_by_id
+    @arity_      = nil
+  end
+
+  def arity
+    @arity_ = @edges.map { |e| e.arity }.max if !@arity_
+    return @arity_
+  end
+
+  def reset
+    @edges.each { |e| e.mark = 0 }
+  end
+
+  def to_s
+    "Hypergraph<nodes:#{@nodes.size}, edges:#{@edges.size}, arity=#{arity}>"
+  end
+
+  def to_json weights=nil
+    json_s = "{\n"
+    json_s += "\"weights\":#{(weights ? weights.to_json : '{}')},\n"
+    json_s += "\"nodes\":\n"
+    json_s += "[\n"
+    json_s += @nodes.map { |n|
+      "{ \"id\":#{n.id}, \"cat\":\"#{n.symbol.to_json.slice(1..-1).chomp('"')}\", \"span\":[#{n.left},#{n.right}] }"
+    }.join ",\n"
+    json_s += "\n],\n"
+    json_s += "\"edges\":\n"
+    json_s += "[\n"
+    json_s += @edges.map { |e|
+      "{ \"head\":#{e.head.id}, \"rule\":#{e.rule.to_json}, \"tails\":#{e.tails.map{ |n| n.id }}, \"f\":#{(e.f ? e.f.to_json : '{}')} }"
+    }.join ",\n"
+    json_s += "\n]\n"
+    json_s += "}\n"
+
+    return json_s
+
+  end
+end
+
+class HG::Hyperedge
+  attr_accessor :head, :tails, :score, :f, :mark, :rule
+
+  def initialize head=Node.new, tails=[], score=0.0, f=SparseVector.new, rule=nil
+    @head   = head
+    @tails  = tails
+    @score  = score
+    @f      = f
+    @mark   = 0
+    @rule   = (rule.class==String ? Grammar::Rule.from_s(rule) : rule)
+  end
+
+  def arity
+    return @tails.size
+  end
+
+  def marked?
+    arity == @mark
+  end
+
+  def to_s
+    "Hyperedge<head=#{@head.id}, rule:'#{@rule.to_s}', tails=#{@tails.map{|n|n.id}}, arity=#{arity}, score=#{@score}, f=#{f.to_s}, mark=#{@mark}>"
+  end
+end
+
+def HG::topological_sort nodes
+  sorted = []
+  s = nodes.reject { |n| !n.incoming.empty? }
+  while !s.empty?
+    sorted << s.shift
+    sorted.last.outgoing.each { |e|
+      next if e.marked?
+      e.mark += 1
+      s << e.head if e.head.incoming.reject{ |f| f.marked? }.empty?
+    }
+  end
+  return sorted
+end
+
+def HG::init nodes, semiring, root
+  nodes.each { |n| n.score=semiring.null }
+  root.score = semiring.one
+end
+
+def HG::viterbi hypergraph, root, semiring=ViterbiSemiring.new
+  toposorted = topological_sort hypergraph.nodes
+  init toposorted, semiring, root
+  toposorted.each { |n|
+    n.incoming.each { |e|
+      s = semiring.one
+      e.tails.each { |m|
+        s = semiring.multiply.call(s, m.score)
+      }
+      n.score = semiring.add.call(n.score, semiring.multiply.call(s, e.score))
+    }
+  }
+end
+
+def HG::viterbi_path hypergraph, root, semiring=ViterbiSemiring.new
+  toposorted = topological_sort hypergraph.nodes
+  init toposorted, semiring, root
+  best_path = []
+  toposorted.each { |n|
+    best_edge = nil
+    n.incoming.each { |e|
+      s = semiring.one
+      e.tails.each { |m|
+        s = semiring.multiply.call(s, m.score)
+      }
+      if n.score < semiring.multiply.call(s, e.score) # ViterbiSemiring add
+        best_edge = e
+      end
+      n.score = semiring.add.call(n.score, semiring.multiply.call(s, e.score))
+    }
+    best_path << best_edge if best_edge
+  }
+  return best_path, toposorted.last.score
+end
+
+def HG::k_best hypergraph, root, semiring=nil
+  #TODO
+end
+
+def HG::all_paths hypergraph, root
+  toposorted = topological_sort hypergraph.nodes
+  paths = [[]]
+  toposorted.each { |n|
+    next if n.incoming.empty?
+    new_paths = []
+    while !paths.empty?
+      p = paths.pop
+      n.incoming.each { |e|
+        new_paths << p+[e]
+      }
+    end
+    paths = new_paths
+  }
+  return paths
+end
+
+def HG::derive path, cur, carry
+  edge = path.select { |e|    e.head.symbol==cur.symbol \
+                           && e.head.left==cur.left \
+                           && e.head.right==cur.right }.first
+  j = 0
+  edge.rule.target.each { |i|
+    if i.class == Grammar::NT
+      derive path, edge.tails[edge.rule.map[j]], carry
+      j += 1
+    else
+      carry << i
+    end
+  }
+  return carry
+end
+
+def HG::read_hypergraph_from_json fn, semiring=RealSemiring.new, log_weights=false
+  nodes = []
+  edges = []
+  nodes_by_id = {}
+  h = JSON.parse File.new(fn).read
+  w = SparseVector.from_h h['weights']
+  h['nodes'].each { |x|
+    n = Node.new x['id'], x['symbol'], x['span']
+    nodes << n
+    nodes_by_id[n.id] = n
+  }
+  h['edges'].each { |x|
+    e = Hyperedge.new(nodes_by_id[x['head']], \
+                      x['tails'].map { |j| nodes_by_id[j] }.to_a, \
+                      (x['score'] ? semiring.convert.call(x['score'].to_f) : nil), \
+                      (x['f'] ? SparseVector.from_h(x['f']) : SparseVector.new), \
+                      x['rule'])
+    if x['f']
+      if log_weights
+        e.score = Math.exp(w.dot(e.f))
+      else
+        e.score = w.dot(e.f)
+      end
+    end
+    e.tails.each { |m|
+      m.outgoing << e
+    }
+    e.head.incoming << e
+    edges << e
+  }
+  return Hypergraph.new(nodes, edges), nodes_by_id
+end
+
+end #module
+
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