From 3acdf1e4b37637d6df86a7b54fb0f1b0464c172b Mon Sep 17 00:00:00 2001
From: Victor Chahuneau <vchahune@cs.cmu.edu>
Date: Wed, 6 Jun 2012 01:10:49 -0400
Subject: Python - Added hypergraph functionnality

- k-best translations
- 1-best, k-best structures
- sample derivations from the forest
- intersect hypergraph and lattice
- lattice
---
 python/src/_cdec.pyx | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 84 insertions(+), 3 deletions(-)

(limited to 'python/src/_cdec.pyx')

diff --git a/python/src/_cdec.pyx b/python/src/_cdec.pyx
index b99f087d..45320c46 100644
--- a/python/src/_cdec.pyx
+++ b/python/src/_cdec.pyx
@@ -1,8 +1,11 @@
 from libcpp.string cimport string
 from libcpp.vector cimport vector
+from cython.operator cimport dereference as deref
 from utils cimport *
 cimport hypergraph
 cimport decoder
+cimport lattice
+cimport kbest as kb
 
 SetSilent(True)
 
@@ -16,13 +19,13 @@ cdef class Weights:
         self.weights = &decoder.dec.CurrentWeightVector()
 
     def __getitem__(self, char* fname):
-        cdef unsigned fid = Convert(fname)
+        cdef unsigned fid = FDConvert(fname)
         if fid <= self.weights.size():
             return self.weights[0][fid]
         raise KeyError(fname)
     
     def __setitem__(self, char* fname, float value):
-        cdef unsigned fid = Convert(<char *>fname)
+        cdef unsigned fid = FDConvert(<char *>fname)
         if self.weights.size() <= fid:
             self.weights.resize(fid + 1)
         self.weights[0][fid] = value
@@ -30,7 +33,7 @@ cdef class Weights:
     def __iter__(self):
         cdef unsigned fid
         for fid in range(1, self.weights.size()):
-            yield Convert(fid).c_str(), self.weights[0][fid]
+            yield FDConvert(fid).c_str(), self.weights[0][fid]
 
 cdef class Decoder:
     cdef decoder.Decoder* dec
@@ -66,6 +69,7 @@ cdef class Decoder:
                 fname, value = line.split()
                 self.weights[fname.strip()] = float(value)
 
+    # TODO: list, lattice translation
     def translate(self, unicode sentence, grammar=None):
         if grammar:
             self.dec.SetSentenceGrammarFromString(string(<char *> grammar))
@@ -81,6 +85,12 @@ cdef class Decoder:
     
 cdef class Hypergraph:
     cdef hypergraph.Hypergraph* hg
+    cdef MT19937* rng
+
+    def __dealloc__(self):
+        del self.hg
+        if self.rng != NULL:
+            del self.rng
 
     def viterbi(self):
         assert (self.hg != NULL)
@@ -89,6 +99,77 @@ cdef class Hypergraph:
         cdef str sentence = GetString(trans).c_str()
         return sentence.decode('utf8')
 
+    def viterbi_tree(self):
+        assert (self.hg != NULL)
+        cdef str tree = hypergraph.ViterbiETree(self.hg[0]).c_str()
+        return tree.decode('utf8')
+
+    def kbest(self, size):
+        assert (self.hg != NULL)
+        cdef kb.KBestDerivations[vector[WordID], kb.ESentenceTraversal]* derivations = new kb.KBestDerivations[vector[WordID], kb.ESentenceTraversal](self.hg[0], size)
+        cdef kb.KBestDerivations[vector[WordID], kb.ESentenceTraversal].Derivation* derivation
+        cdef str tree
+        cdef unsigned k
+        for k in range(size):
+            derivation = derivations.LazyKthBest(self.hg.nodes_.size() - 1, k)
+            if not derivation: break
+            tree = GetString(derivation._yield).c_str()
+            yield tree.decode('utf8')
+        del derivations
+
+    def kbest_tree(self, size):
+        assert (self.hg != NULL)
+        cdef kb.KBestDerivations[vector[WordID], kb.ETreeTraversal]* derivations = new kb.KBestDerivations[vector[WordID], kb.ETreeTraversal](self.hg[0], size)
+        cdef kb.KBestDerivations[vector[WordID], kb.ETreeTraversal].Derivation* derivation
+        cdef str sentence
+        cdef unsigned k
+        for k in range(size):
+            derivation = derivations.LazyKthBest(self.hg.nodes_.size() - 1, k)
+            if not derivation: break
+            sentence = GetString(derivation._yield).c_str()
+            yield sentence.decode('utf8')
+        del derivations
+
+    def intersect(self, Lattice lat):
+        assert (self.hg != NULL)
+        hypergraph.Intersect(lat.lattice[0], self.hg)
+
+    def sample(self, unsigned n):
+        assert (self.hg != NULL)
+        cdef vector[hypergraph.Hypothesis]* hypos = new vector[hypergraph.Hypothesis]()
+        if self.rng == NULL:
+            self.rng = new MT19937()
+        hypergraph.sample_hypotheses(self.hg[0], n, self.rng, hypos)
+        cdef str sentence
+        cdef unsigned k
+        for k in range(hypos.size()):
+            sentence = GetString(hypos[0][k].words).c_str()
+            yield sentence.decode('utf8')
+        del hypos
+
+    # TODO: get feature expectations, get partition function ("inside" score)
+    # TODO: reweight the forest with different weights (Hypergraph::Reweight)
+    # TODO: inside-outside pruning
+
+cdef class Lattice:
+    cdef lattice.Lattice* lattice
+
+    def __init__(self, tuple plf_tuple):
+        self.lattice = new lattice.Lattice()
+        cdef bytes plf = str(plf_tuple)
+        hypergraph.PLFtoLattice(string(<char *>plf), self.lattice)
+
+    def __str__(self):
+        return hypergraph.AsPLF(self.lattice[0]).c_str()
+
+    def __iter__(self):
+        return iter(eval(str(self)))
+
+    def __dealloc__(self):
+        del self.lattice
+
+# TODO: wrap SparseVector
+
 """
 def params_str(params):
     return '\n'.join('%s=%s' % (param, value) for param, value in params.iteritems())
-- 
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