suffix-thumb

find the optimal transormations between sets of words

npm install suffix-thumb

discover the minimal rules for mapping two sets of words to one another, according to changes in their suffix.

It was built for learning rules about verb conjugations, but in a way, it is just a generic compression algorithm.

The assumption is that a word's _suffix_ is the most-often changed part of a word.

!preview

$3

``js
import { learn, convert } from 'suffix-thumb'

let pairs = [
['walk', 'walked'],
['talk', 'talked'],
['go', 'went'],
]
let model = learn(pairs)
/* {
rules: { k: [ [ 'alk', 'alked' ] ] },
exceptions: { go: 'went' },
}*/

let out = convert('walk', model)
// 'walked'
`

you can pass-in options:
`js
let opts={
threshold:80, //how sloppy our initial rules can be
min:0, //rule must satisfy # of pairs
reverse:true, //compute backward transformation, too
}
let model = learn(pairs, opts)
`



$3

let pairs = [
['walk', 'walked'],
['talk', 'talked'],
['go', 'went'],
]
let model = learn(pairs)
let rev = reverse(model)
let out = convert('walked', rev)
// 'walk'
`
by default, the model ensures all two-way transformation - if you only require 1-way, you can do:
`js
learn(pairs, {reverse: false})
`
you can expect the model to be 5% smaller or so - not much.

$3

`js
import { learn, compress, uncompress, convert } from 'suffix-thumb'

let pairs = [
['walk', 'walked'],
['talk', 'talked'],
['go', 'went'],
]
let model = learn(pairs)
// shrink it
model = compress(shrink)
// {rules:'LSKs3H2-LNL.S3DH'}
// pop it back
model = uncompress(model)
let out = convert('walk', model)
// 'walked'

`
The models must be uncompressed before they are used, or reversed.

$3

If you are just doing one-way transformation, and not reverse, you may want to allow duplicates on the right side:
`js
let pairs = [
['left', 'right'],
['ok', 'right'],
]
let model = learn(pairs, {reverse: false})
let out = convert('ok', model)
// 'right'
`


How it works

For each word-pair, it generates all n-suffixes of the left-side, and n-suffixes of the right-side.

any good correlations between the two suffix pairs begins to pop out. Exceptions to these rules are remembered. It then exhaustively reduces any redundancies in these rules.

There are some compromises, magic-numbers, and opinionated decisions - in-order to allow productive, but imperfect rules.

* The library is meant optimize for file-size of the model
* compression is slow, uncompression is fast
* it should always return a perfect result

The library drops case-information - and numbers and some characters1 will not compress properly.

There may be wordlists with few helpful patterns. Conjugation datasets in English and French tend to get ~85% filesize compression.

$3

* efrt - trie-based prefix compression for JSON

MIT