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#!/usr/bin/env python
# Usage: extract-target-trees.py [FILE]
#
# Reads moses-chart's -T output from FILE or standard input and writes trees to
# standard output in Moses' XML tree format.
import re
import sys
class Tree:
def __init__(self, label, children):
self.label = label
self.children = children
def is_leaf(self):
return len(self.children) == 0
class Derivation(list):
def find_root(self):
assert len(self) > 0
root = None
for hypothesis in self:
if hypothesis.span[0] != 0:
continue
if root == None or hypothesis.span[1] > root.span[1]:
root = hypothesis
assert root
return root
def construct_target_tree(self):
map = {}
for hypothesis in self:
map[hypothesis.span] = hypothesis
root = self.find_root()
return self._buildTree(root, map)
def _buildTree(self, root, map):
def escapeLabel(label):
s = label.replace("&", "&")
s = s.replace("<", "<")
s = s.replace(">", ">")
return s
# Build list of NT spans in source order...
nonTermSpans = []
for item in root.sourceSymbolInfo:
span = item[0]
if span in map: # In map iff symbol is NT
nonTermSpans.append(span)
nonTermSpans.sort()
# ... then convert to target order.
alignmentPairs = root.ntAlignments[:]
alignmentPairs.sort()
targetOrderNonTermSpans = {}
for i, pair in enumerate(alignmentPairs):
targetOrderNonTermSpans[pair[1]] = nonTermSpans[i]
children = []
numNonTerms = 0
for i, symbol in enumerate(root.targetRHS):
if i in targetOrderNonTermSpans:
hyp = map[targetOrderNonTermSpans[i]]
children.append(self._buildTree(hyp, map))
numNonTerms += 1
else:
children.append(Tree(escapeLabel(symbol), []))
assert numNonTerms == len(root.ntAlignments)
return Tree(root.targetLHS, children)
class Hypothesis:
def __init__(self):
self.sentenceNum = None
self.span = None
self.sourceSymbolInfo = None
self.targetLHS = None
self.targetRHS = None
self.ntAlignments = None
def __str__(self):
return str(self.id) + " " + str(self.component_scores)
def readDerivations(input, lineNum):
prevSentenceNum = None
derivation = Derivation()
for line in input:
lineNum += 1
hypothesis = parseLine(line)
if hypothesis.sentenceNum != prevSentenceNum:
# We've started reading the next derivation...
prevSentenceNum = hypothesis.sentenceNum
if len(derivation):
yield derivation, lineNum
derivation = Derivation()
derivation.append(hypothesis)
if len(derivation):
yield derivation, lineNum
# Extract the hypothesis components and return a Hypothesis object.
def parseLine(s):
pattern = r"Trans Opt (\d+) " + \
r"\[(\d+)\.\.(\d+)\]:" + \
r"((?: \[\d+\.\.\d+\]=\S+ )+):" + \
r" (\S+) ->" + \
r"((?:\S+ )+):" + \
r"((?:\d+-\d+ )*): pC="
regexp = re.compile(pattern)
match = regexp.match(s)
if not match:
sys.stderr.write("%s\n" % s)
assert match
group = match.groups()
hypothesis = Hypothesis()
hypothesis.sentenceNum = int(group[0]) + 1
hypothesis.span = (int(group[1]), int(group[2]))
hypothesis.sourceSymbolInfo = []
for item in group[3].split():
pattern = "\[(\d+)\.\.(\d+)\]=(\S+)"
regexp = re.compile(pattern)
match = regexp.match(item)
assert(match)
start, end, symbol = match.groups()
span = (int(start), int(end))
hypothesis.sourceSymbolInfo.append((span, symbol))
hypothesis.targetLHS = group[4]
hypothesis.targetRHS = group[5].split()
hypothesis.ntAlignments = []
for pair in group[6].split():
match = re.match(r'(\d+)-(\d+)', pair)
assert match
ai = (int(match.group(1)), int(match.group(2)))
hypothesis.ntAlignments.append(ai)
return hypothesis
def tree_to_xml(tree):
if tree.is_leaf():
return tree.label
else:
s = '<tree label="%s"> ' % tree.label
for child in tree.children:
s += tree_to_xml(child)
s += " "
s += '</tree>'
return s
def main():
if len(sys.argv) > 2:
sys.stderr.write("usage: %s [FILE]\n" % sys.argv[0])
sys.exit(1)
if len(sys.argv) == 1 or sys.argv[1] == "-":
input = sys.stdin
else:
input = open(sys.argv[1])
lineNum = 0
for derivation, lineNum in readDerivations(input, lineNum):
try:
tree = derivation.construct_target_tree()
except:
msg = "error processing derivation at line %d\n" % lineNum
sys.stderr.write(msg)
raise
print tree_to_xml(tree)
if __name__ == '__main__':
main()
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