NGramMap (Dataflow Library Distribution Project 7.0.2-37 API)

java.lang.Object
- com.pervasive.datarush.analytics.text.NGramMap

Direct Known Subclasses:

WordMap
```
public class NGramMap
extends Object
```
Implementation of an n-gram model. An n-gram model is a type of probabilistic language model for predicting the next item in a sequence based on the previous items in the sequence.

Field Summary

Fields
Modifier and Type Field and Description

protected TreeMap<NGram,Integer> map

Fields
Modifier and Type	Field and Description
`protected TreeMap<NGram,Integer>`	`map`

Constructor Summary

Constructors
Constructor and Description
`NGramMap()` Default constructor
`NGramMap(int n)` Create an n-gram to frequency map.
`NGramMap(int n, Map<NGram,Integer> map)` Create an n-gram to frequency map.
`NGramMap(int n, Map<NGram,Integer> map, int textSize)` Create an n-gram to frequency map.
`NGramMap(NGramMap map)` Copy an n-gram to frequency map.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`int`	`calcOrigTextSize()` Calculates the total number of elements in the original text based on the current contents of the map.
`boolean`	`decreaseFreq(NGram nGram)` Removes an n-gram from the map or decrease the frequency if the absolute frequency is greater than one.
`boolean`	`equals(Object obj)`
`void`	`filterByThreshold(int min, int max)` Filters this n-gram map of all frequencies between min and max inclusively.
`void`	`filterByTotal(int total)` Filters this n-gram map of all but the top frequencies.
`static TokenDecoder`	`getDecoder()`
`static TokenEncoder`	`getEncoder()`
`int`	`getFrequency(NGram ngram)` Get the absolute frequency of an NGram in the map.
`List<Integer>`	`getFrequencyList()` Get an ordered list of the absolute frequencies contained in the map.
`Map<NGram,Integer>`	`getMap()` Get a copy of the map that backs this object.
`int`	`getN()` Get the degree of the n-grams in this map.
`List<NGram>`	`getNGramList()` Get an ordered list of the n-grams contained in the map.
`int`	`getOrigTextSize()` Get the total number of elements in the original text.
`double`	`getProbability(NGram ngram)` Get the relative frequency of an n-gram in the map.
`List<Double>`	`getProbabilityList()` Get an ordered list of the relative frequencies contained in the map.
`int`	`hashCode()`
`boolean`	`increaseFreq(NGram nGram)` Adds an n-gram to the map or increases the frequency if it is already present.
`Iterator<Map.Entry<NGram,Integer>>`	`iterator()` Get an iterator over the entries in the map.
`int`	`removeNGram(NGram nGram)` Removes an n-gram from the map.
`void`	`setOrigTextSize(int origTextSize)` Set the total number of elements in the original text.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - map
```
protected TreeMap<NGram,Integer> map
```
- Constructor Detail
  - NGramMap
```
public NGramMap()
```
    Default constructor
  - NGramMap
```
public NGramMap(int n)
```
    Create an n-gram to frequency map.
    
    Parameters:
    
    n - the degree of the NGrams in the map
  - NGramMap
```
public NGramMap(int n,
                Map<NGram,Integer> map)
```
    Create an n-gram to frequency map.
    
    Parameters:
    
    n - the degree of the NGrams in the map
    
    map - the mappings to use
  - NGramMap
```
public NGramMap(int n,
                Map<NGram,Integer> map,
                int textSize)
```
    Create an n-gram to frequency map.
    
    Parameters:
    
    n - the degree of the NGrams in the map
    
    map - the mappings to use
    
    textSize - the number of elements in the original text
  - NGramMap
```
public NGramMap(NGramMap map)
```
    Copy an n-gram to frequency map.
    
    Parameters:
    
    map - the n-gram map to copy
- Method Detail
  - getN
```
public int getN()
```
    Get the degree of the n-grams in this map.
    
    Returns:
    
    the n used by the NGrams in this map
  - getOrigTextSize
```
public int getOrigTextSize()
```
    Get the total number of elements in the original text.
    
    Returns:
    
    the origTextSize used to calculate the relative frequencies
  - setOrigTextSize
```
public void setOrigTextSize(int origTextSize)
```
    Set the total number of elements in the original text.
    
    Parameters:
    
    origTextSize - the total number of words in the original text
  - getNGramList
```
public List<NGram> getNGramList()
```
    Get an ordered list of the n-grams contained in the map.
    
    Returns:
    
    the list of NGrams
  - getFrequencyList
```
public List<Integer> getFrequencyList()
```
    Get an ordered list of the absolute frequencies contained in the map.
    
    Returns:
    
    the list of frequencies
  - getProbabilityList
```
public List<Double> getProbabilityList()
```
    Get an ordered list of the relative frequencies contained in the map.
    
    Returns:
    
    the list of frequencies
  - getMap
```
public Map<NGram,Integer> getMap()
```
    Get a copy of the map that backs this object.
    
    Returns:
    
    map of Ngrams to Integers
  - calcOrigTextSize
```
public int calcOrigTextSize()
```
    Calculates the total number of elements in the original text based on the current contents of the map. This will only be accurate if the map is not a subset of the original model created from the text.
    
    Returns:
    
    the total of all elements in the map
  - iterator
```
public Iterator<Map.Entry<NGram,Integer>> iterator()
```
    Get an iterator over the entries in the map.
    
    Returns:
    
    an iterator over the map entries
  - getFrequency
```
public int getFrequency(NGram ngram)
```
    Get the absolute frequency of an NGram in the map.
    
    Parameters:
    
    ngram - the n-gram to get the frequency of
    
    Returns:
    
    the absolute frequency of the n-gram
  - getProbability
```
public double getProbability(NGram ngram)
```
    Get the relative frequency of an n-gram in the map. If the OrigTextSize has not been set will calculate based current map.
    
    Parameters:
    
    ngram - the n-gram to get the frequency of
    
    Returns:
    
    the relative frequency of the n-gram
  - increaseFreq
```
public boolean increaseFreq(NGram nGram)
```
    Adds an n-gram to the map or increases the frequency if it is already present.
    
    Parameters:
    
    nGram - element to increase the frequency of in the map
    
    Returns:
    
    true if n-gram is valid and could be incremented
  - decreaseFreq
```
public boolean decreaseFreq(NGram nGram)
```
    Removes an n-gram from the map or decrease the frequency if the absolute frequency is greater than one.
    
    Parameters:
    
    nGram - element to decrease the frequency of in the map
    
    Returns:
    
    true if n-gram is valid and could be decremented
  - removeNGram
```
public int removeNGram(NGram nGram)
```
    Removes an n-gram from the map.
    
    Parameters:
    
    nGram - element to remove from the map
    
    Returns:
    
    the frequency previously associated with the n-gram or null
  - filterByThreshold
```
public void filterByThreshold(int min,
                              int max)
```
    Filters this n-gram map of all frequencies between min and max inclusively.
    
    Parameters:
    
    min - the smallest frequency to keep
    
    max - the largest frequency to keep
  - filterByTotal
```
public void filterByTotal(int total)
```
    Filters this n-gram map of all but the top frequencies.
    
    Parameters:
    
    total - number of top frequencies to keep
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object obj)
```
    Overrides:
    
    equals in class Object
  - getEncoder
```
public static TokenEncoder getEncoder()
```
  - getDecoder
```
public static TokenDecoder getDecoder()
```

Class NGramMap

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

map

Constructor Detail

NGramMap

NGramMap

NGramMap

NGramMap

NGramMap

Method Detail

getN

getOrigTextSize

setOrigTextSize

getNGramList

getFrequencyList

getProbabilityList

getMap

calcOrigTextSize

iterator

getFrequency

getProbability

increaseFreq

decreaseFreq

removeNGram

filterByThreshold

filterByTotal

toString

hashCode

equals

getEncoder

getDecoder