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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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