From 94fef2d3aac6d7380e92771c46cc0e4655afaea4 Mon Sep 17 00:00:00 2001
From: Patrick Simianer <p@simianer.de>
Date: Sun, 1 Jun 2014 23:23:14 +0200
Subject: add grammar.rb, hg.rb: viterbi_path(), all_paths()

---
 README.md          |  1 +
 lib/nlp_ruby.rb    |  3 ++-
 lib/nlp_ruby/hg.rb | 52 ++++++++++++++++++++++++++++++++++++++++++++++++----
 nlp_ruby.gemspec   |  2 +-
 4 files changed, 52 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 338109c..cc8d3ef 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,7 @@ The .gem can be found here: https://rubygems.org/gems/nlp_ruby
          bleu.rb : BLEU implementation, also per-sentence-BLEU
           dag.rb : implementation of a directed acyclic graph and various algorithms
      fileutil.rb : file utilities
+      grammar.rb : classes to model grammars (mostly for translation grammars)
            hg.rb : data structures and algorithms (viterbi currently) for hypergraphs
          misc.rb : misc. stuff (e.g. monkey patches for Array and String)
     semirings.rb : semirings (used in dags.rb)
diff --git a/lib/nlp_ruby.rb b/lib/nlp_ruby.rb
index f57a302..0e26e97 100755
--- a/lib/nlp_ruby.rb
+++ b/lib/nlp_ruby.rb
@@ -10,8 +10,9 @@ require 'nlp_ruby/semirings'
 require 'nlp_ruby/bleu'
 require 'nlp_ruby/misc'
 require 'nlp_ruby/hg'
+require 'nlp_ruby/grammar'
 
-STDIN.set_encoding 'utf-8'
+STDIN.set_encoding  'utf-8'
 STDOUT.set_encoding 'utf-8'
 STDERR.set_encoding 'utf-8'
 
diff --git a/lib/nlp_ruby/hg.rb b/lib/nlp_ruby/hg.rb
index b49cc6e..66e3b13 100644
--- a/lib/nlp_ruby/hg.rb
+++ b/lib/nlp_ruby/hg.rb
@@ -3,6 +3,7 @@
 require 'nlp_ruby'
 require 'json'
 
+
 module HG
 
 
@@ -40,14 +41,15 @@ class HG::Hypergraph
 end
 
 class HG::Hyperedge
-  attr_accessor :head, :tails, :weight, :f, :mark
+  attr_accessor :head, :tails, :weight, :f, :mark, :rule, :left, :right
 
-  def initialize head=nil, tails=[], weight=0.0, f={}
+  def initialize head=nil, tails=[], weight=0.0, f={}, rule=nil, left=nil, right=nil
     @head   = head
     @tails  = tails
     @weight = weight
     @f      = f
     @mark   = 0
+    @rule   = Grammar::Rule.from_s rule if rule
   end
 
   def arity
@@ -59,7 +61,7 @@ class HG::Hyperedge
   end
 
   def to_s
-    "Hyperedge<head:\"#{@head.label}\", tails:#{@tails.map{|n|n.label}}, arity:#{arity}, weight:#{@weight}, f:#{f.to_s}, mark:#{@mark}>"
+    "Hyperedge<head:\"#{@head.label}\", rule:\"#{@rule.to_s}, \"tails:#{@tails.map{|n|n.label}}, arity:#{arity}, weight:#{@weight}, f:#{f.to_s}, mark:#{@mark}>"
   end
 end
 
@@ -96,6 +98,27 @@ def HG::viterbi hypergraph, root, semiring=ViterbiSemiring.new
   }
 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.weight) # ViterbiSemiring add
+        best_edge = e
+      end
+      n.score = semiring.add.call(n.score, semiring.multiply.call(s, e.weight))
+    }
+    best_path << best_edge
+  }
+  return best_path, toposorted.last.score
+end
+
 def HG::read_hypergraph_from_json fn, semiring=RealSemiring.new, log_weights=false
   nodes = []
   edges = []
@@ -110,7 +133,11 @@ def HG::read_hypergraph_from_json fn, semiring=RealSemiring.new, log_weights=fal
     nodes_by_index << n
   }
   h['edges'].each { |i|
-    e = Hyperedge.new nodes_by_label[i['head']], i['tails'].map{|j| nodes_by_label[j]}.to_a, semiring.convert.call(i['weight'].to_f)
+    e = Hyperedge.new(nodes_by_label[i['head']], \
+                      i['tails'].map{|j| nodes_by_label[j]}.to_a, \
+                      semiring.convert.call(i['weight'].to_f), \
+                      {}, \
+                      i['rule'], i['left'], i['right'])
     e.f = SparseVector.from_h i['f']
     if log_weights
       e.weight = Math.exp(w.dot(e.f))
@@ -126,6 +153,23 @@ def HG::read_hypergraph_from_json fn, semiring=RealSemiring.new, log_weights=fal
   return Hypergraph.new(nodes, edges), nodes_by_label, nodes_by_index
 end
 
+def HG::all_paths hypergraph, root, semiring=ViterbiSemiring.new
+  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
+
 
 end #module
 
diff --git a/nlp_ruby.gemspec b/nlp_ruby.gemspec
index 1b7ac8d..a5a26df 100644
--- a/nlp_ruby.gemspec
+++ b/nlp_ruby.gemspec
@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
   s.name        = 'nlp_ruby'
-  s.version     = '0.4.1'
+  s.version     = '0.4.2'
   s.date        = '2014-03-10'
   s.summary     = 'nlp_ruby'
   s.description = 'NLP related tools and classes'
-- 
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