SIFT 4


Install via npm

``sh
$ npm install sift-distance
`

NOTE: The major version of this module tracks the algorithm's version.
So, if you want to use SIFT 3, for example, you'd install sift-distance@3.0, for version 3B of the SIFT algorithm sift-distance@3.1, for version 4 sift-distance@4.0 and so on.

About

This implements the SIFT4 extended version.

API

#### SIFT( a, b, [options] )

- String|Buffer|Array a
- String|Buffer|Array b
- Object options
- Number maxOffset
- Number maxDistance
- Function tokenizer
- Function tokenMatcher
- Function matchEvaluator
- Function lengthEvaluator
- Function transpositionEvaluator

$3

#### Number maxOffset

The maximum largest common substring offset to be matched against one another. Defaults to 5.

#### Number maxDistance

Distance at which the algorithm should stop computing the value and just exit (the values are too different anyway).

#### Function tokenizer( value ) -> String|Array|Buffer

- Mixed value

Function to transform strings into vectors of tokens.

#### Function tokenMatcher( token1, token2 ) -> Boolean

- Mixed token1
- Mixed token2

Function to determine if two tokens match each other (equal).

#### Function matchEvaluator( token1, token2 ) -> Number

- Mixed token1
- Mixed token2

Function to determine the way a token match should be added to the lcs (largest common substring). For example, a fuzzy match could be implemented.

#### Function lengthEvaluator( lcs ) -> Number

- Number lcs: largest common substring length

Function to determine the way the lcs value is added to the lcss. For example, longer continuous substrings could be awarded.

#### Function transpositionEvaluator( transpositions, lcss ) -> Number

- Number transpositions: number of transpositions
- Number lcss`: largest common subsequence length

Function to determine the way the number of transpositions affects the final result.