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java.lang.Objectedu.stanford.nlp.parser.prefixparser.PrefixProbabilityParser
public class PrefixProbabilityParser
An implementation of the Stolcke 1995 chart parsing algorithm that calculates the prefix probability of a string S with respect to a probabilistic context-free grammar G. The prefix probability is defined as the total probability of the set of all trees T such that S is a prefix of T. As a side effect, the parser also calculates the total probability of S being a complete sentence in G.
The intended usage is as follows: a PrefixProbabilityParser is vended by thePrefixProbabilityParserGenerator.getParser()
method of a a PrefixProbabilityParserGenerator
generator instance, which in turn is obtained by training a generator on a collection of context-free trees (see the
PrefixProbabilityParserGenerator.getGenerator(edu.stanford.nlp.trees.Treebank, java.lang.String)
method).
Then use the loadSentence(java.util.List)
method to load a sentence (a List
of words (Strings)) into the parser.
The parse chart for the string can then be incrementally constructed with the parseNextWord()
method.
At any time, the current prefix probability and string probability of the words parsed so far can be accessed with the
prefixProbability()
and stringProbability()
methods respectively. See the source code of the main method
of this class for further details of use.
Method Summary | |
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boolean |
hasNextWord()
returns true iff there is another word in the loaded sentence that has not been parsed yet |
void |
loadSentence(java.util.List<java.lang.String> sentence)
Loads a sentence (a List of Strings) into the parser for parsing. |
static void |
main(java.lang.String[] args)
|
void |
parseNextWord()
call this method to read in the next word from the input and build the corresponding chart entries |
void |
parseSentences(java.io.Reader r)
Parse a list of pre-tokenized sentences, one per line, from a Reader. |
double |
prefixProbability()
Returns the total probability for prefix parses of the string prefix parsed so far. |
java.lang.String |
previousWord()
returns the previous word parsed. |
double |
stringProbability()
Returns the total probability of complete parses for the string prefix parsed so far. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Method Detail |
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public void loadSentence(java.util.List<java.lang.String> sentence)
public boolean hasNextWord()
public java.lang.String previousWord()
public void parseNextWord()
public double stringProbability()
public double prefixProbability()
public static void main(java.lang.String[] args) throws java.lang.Exception
java.lang.Exception
public void parseSentences(java.io.Reader r) throws java.io.IOException
java.io.IOException
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