ContextEncodedNgramLanguageModel

Type Parameters:

W -

All Superinterfaces:

NgramLanguageModel<W>

All Known Implementing Classes:

AbstractContextEncodedNgramLanguageModel, ContextEncodedCachingLmWrapper, ContextEncodedProbBackoffLm
```
public interface ContextEncodedNgramLanguageModel<W>
extends NgramLanguageModel<W>
```
Interface for language models which expose the internal context-encoding for more efficient queries. (Note: language model implementations may internally use a context-encoding without implementing this interface). A context-encoding encodes an n-gram as a integer representing the last word, and an offset which serves as a logical pointer to the (n-1) prefix words. The integers represent words of type W in the vocabulary, and the mapping from the vocabulary to integers is managed by an instance of the WordIndexer class.

Author:

adampauls

Nested Class Summary

Nested Classes
Modifier and Type	Interface	Description
`static class`	`ContextEncodedNgramLanguageModel.DefaultImplementations`
`static class`	`ContextEncodedNgramLanguageModel.LmContextInfo`	Simple class for returning context offsets

Nested classes/interfaces inherited from interface edu.berkeley.nlp.lm.NgramLanguageModel
NgramLanguageModel.StaticMethods

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`float`	`getLogProb(long contextOffset, int contextOrder, int word, ContextEncodedNgramLanguageModel.LmContextInfo outputContext)`	Get the score for an n-gram, and also get the context offset of the n-gram's suffix.
`int[]`	`getNgramForOffset(long contextOffset, int contextOrder, int word)`	Gets the n-gram referred to by a context-encoding.
`ContextEncodedNgramLanguageModel.LmContextInfo`	`getOffsetForNgram(int[] ngram, int startPos, int endPos)`	Gets the offset which refers to an n-gram.

Methods inherited from interface edu.berkeley.nlp.lm.NgramLanguageModel
getLmOrder, getLogProb, getWordIndexer, scoreSentence, setOovWordLogProb

- Method Detail
  - getLogProb
```
float getLogProb(long contextOffset,
                 int contextOrder,
                 int word,
                 ContextEncodedNgramLanguageModel.LmContextInfo outputContext)
```
    Get the score for an n-gram, and also get the context offset of the n-gram's suffix.
    
    Parameters:
    
    contextOffset - Offset of context (prefix) of an n-gram
    
    contextOrder - The (0-based) length of context (i.e. order == 0 iff context refers to a unigram).
    
    word - Last word of the n-gram
    
    outputContext - Offset of the suffix of the input n-gram. If the parameter is null it will be ignored. This can be passed to future queries for efficient access.
    
    Returns:
  - getOffsetForNgram
```
ContextEncodedNgramLanguageModel.LmContextInfo getOffsetForNgram(int[] ngram,
                                                                 int startPos,
                                                                 int endPos)
```
    Gets the offset which refers to an n-gram. If the n-gram is not in the model, then it returns the shortest suffix of the n-gram which is. This operation is not necessarily fast.
  - getNgramForOffset
```
int[] getNgramForOffset(long contextOffset,
                        int contextOrder,
                        int word)
```
    Gets the n-gram referred to by a context-encoding. This operation is not necessarily fast.