lancaster-stemmer

What is this?
When should I use this?
Install
Use
API
CLI
Types
Compatibility
Related
Contribute
Security
License

What is this?

This package exposes a stemming algorithm. That means it gets a certain string (typically an English word), and turns it into a shorter version (a stem), which can then be compared to other stems (of other words), to check if they are both (likely) the same term.

When should I use this?

You’re probably dealing with natural language and know you need this if you’re here!

Install

This package is ESM only. In Node.js (version 16+), install with npm:

npm install lancaster-stemmer

In Deno with esm.sh:

import {lancasterStemmer} from 'https://esm.sh/lancaster-stemmer@2'

In browsers with esm.sh:

<script type="module">
  import {lancasterStemmer} from 'https://esm.sh/lancaster-stemmer@2?bundle'
</script>

Use

import {lancasterStemmer} from 'lancaster-stemmer'

console.log(lancasterStemmer('considerations')) // => 'consid'
console.log(lancasterStemmer('detestable')) // => 'detest'
console.log(lancasterStemmer('vileness')) // => 'vil'
console.log(lancasterStemmer('giggling')) // => 'giggl'
console.log(lancasterStemmer('anxious')) // => 'anxy'

// Case insensitive
console.log(lancasterStemmer('analytic') === lancasterStemmer('AnAlYtIc')) // => true

API

This package exports the identifier lancasterStemmer. There is no default export.

`lancasterStemmer(value, options?)`

Get the stem from a given value.

Parameters

value(string, required) — value to stem
options(Options, default: {}) — configuration

Returns

Stem for value (string).

`Options`

Configuration (TypeScript type).

Fields

style (Style, default: 'c') — style of algorithm

`Style`

Style of algorithm (TypeScript type).

There are small algorithmic differences between how the algorithm was implemented over the years. Looking at Algorithm Implementations on the archived website, there are four styles available, in addition to the original paper.

The only difference currently implemented in this package is whether a final s is kept before stopping (paper) or dropped before stopping (c).

Values

'c' — rules from the ANSI C (Stark, 1994) and Perl (Taffet, 2001) implementations (compensation -> compen)
'paper' — rules from the original paper (1990), and Pascal (Paice/Husk) and Java (O’Neill, 2000) implementations (compensation -> compens)

CLI

Usage: lancaster-stemmer [options] <words...>

Lancaster stemming algorithm

Options:

  -h, --help           output usage information
  -v, --version        output version number

Usage:

# output stems
$ lancaster-stemmer considerations
consid

# output stems from stdin
$ echo "detestable vileness" | lancaster-stemmer
detest vil

Types

This package is fully typed with TypeScript. It exports the additional types Options and Style.

Compatibility

Projects maintained by the unified collective are compatible with maintained versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line, lancaster-stemmer@^2, compatible with Node.js 12.

stemmer — porter stemmer algorithm
double-metaphone — double metaphone algorithm
soundex-code — soundex algorithm
dice-coefficient — sørensen–dice coefficient
levenshtein-edit-distance — levenshtein edit distance
syllable — syllable count of English words

words/lancaster-stemmer