/**
* TODO(gabor) JavaDoc
*
* @param tokens
* @param seed
* @return
*/
public static Span extractNER(List<CoreLabel> tokens, Span seed) {
// Error checks
if (seed == null) {
return new Span(0, 1);
}
if (seed.start() < 0 || seed.end() < 0) {
return new Span(0, 0);
}
if (seed.start() >= tokens.size() || seed.end() > tokens.size()) {
return new Span(tokens.size(), tokens.size());
}
if (tokens.get(seed.start()).ner() == null) {
return seed;
}
if (seed.start() < 0 || seed.end() > tokens.size()) {
return Span.fromValues(Math.max(0, seed.start()), Math.min(tokens.size(), seed.end()));
}
// Find the span's beginning
int begin = seed.start();
while (begin < seed.end() - 1 && "O".equals(tokens.get(begin).ner())) {
begin += 1;
}
String beginNER = tokens.get(begin).ner();
if (!"O".equals(beginNER)) {
while (begin > 0 && tokens.get(begin - 1).ner().equals(beginNER)) {
begin -= 1;
}
} else {
begin = seed.start();
}
// Find the span's end
int end = seed.end() - 1;
while (end > begin && "O".equals(tokens.get(end).ner())) {
end -= 1;
}
String endNER = tokens.get(end).ner();
if (!"O".equals(endNER)) {
while (end < tokens.size() - 1 && tokens.get(end + 1).ner().equals(endNER)) {
end += 1;
}
} else {
end = seed.end() - 1;
}
// Check that the NER of the beginning and end are the same
if (beginNER.equals(endNER)) {
return Span.fromValues(begin, end + 1);
} else {
String bestNER = guessNER(tokens, Span.fromValues(begin, end + 1));
if (beginNER.equals(bestNER)) {
return extractNER(tokens, Span.fromValues(begin, begin + 1));
} else if (endNER.equals(bestNER)) {
return extractNER(tokens, Span.fromValues(end, end + 1));
} else {
// Something super funky is going on...
return Span.fromValues(begin, end + 1);
}
}
}
