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term-frequency

A simple term frequency library that takes in a document vector, and compiles the frequency calculation of your choosing.

First make the necessary require-ments

``javascript
var sw = require('stopword')
var tf = require('term-frequency');
var tv = require('term-vector');
`


You can then do:

`javascript
var vec = tv.getVector(
sw.removeStopwords(
'This is a really, really cool vector. I like this VeCTor'
.toLowerCase()
.split(/[ ,\.]+/)
)
)
var freq = tf.getTermFrequency(vec);
// freq is now
// [ [ [ 'cool' ], 1 ], [ [ 'really' ], 2 ], [ [ 'vector' ], 2 ] ];
`

Or you can specify a TF scheme like so:

`javascript
var vec = tv.getVector('This is a really, really cool vector. I like this VeCTor');
var freq = tf.getTermFrequency(vec, {scheme: tf.logNormalization});
// freq is now:
// [
// [ [ 'cool' ], 0.6931471805599453 ],
// [ [ 'really' ], 1.0986122886681098 ],
// [ [ 'vector' ], 1.0986122886681098 ]
// ]);
`

Currently supported schemes are

* raw
* logNormalization
* doubleNormalization0point5
* selfString
* selfNumeric

See the Wikipedia page for more info about term frequency calculation

You can also weight your calculations like so. A weight is a numeric
value that will be added to the calculated score.

`javascript
var freq = tf.getTermFrequency(vec, {
scheme: tf.doubleNormalization0point5,
weight: 5
});
// freq is now
// [
// [ [ 'cool' ], 5.7027325540540822 ],
// [ [ 'really' ], 5.9581453659370776 ],
// [ [ 'vector' ], 5.9581453659370776 ]
// ]);
``

[license-image]: http://img.shields.io/badge/license-MIT-blue.svg?style=flat
[license-url]: LICENSE

[npm-url]: https://npmjs.org/package/term-frequency
[npm-version-image]: http://img.shields.io/npm/v/term-frequency.svg?style=flat
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[travis-url]: http://travis-ci.org/fergiemcdowall/term-frequency
[travis-image]: http://img.shields.io/travis/fergiemcdowall/term-frequency.svg?style=flat