// wink-distance
// Distance functions for Bag of Words, Strings,
// Vectors and more.
//
// Copyright (C) GRAYPE Systems Private Limited
//
// This file is part of “wink-distance”.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// Because we want to logically group the variables.
/* eslint sort-vars: 0 */
// ## set
// ### jaccard
/**
*
* Computes the Jaccard distance between input sets `sa` and `sb`.
* This distance is always between 0 and 1.
*
* @method set.jaccard
* @param {set} sa the first set.
* @param {set} sb the second set.
* @return {number} the Jaccard distance between `sa` and `sb`.
*
* @example
* // Set for :-)
* var sa = new Set( ':-)' );
* // Set for :-(
* var sb = new Set( ':-(' );
* jaccard( sa, sb );
* // -> 0.5
*/
var jaccard = function ( sa, sb ) {
var intersectSize = 0;
var distance;
// Use smaller sized set for iteration.
if ( sa.size < sb.size ) {
sa.forEach( function ( element ) {
if ( sb.has( element ) ) intersectSize += 1;
} );
} else {
sb.forEach( function ( element ) {
if ( sa.has( element ) ) intersectSize += 1;
} );
}
// Compute Jaccard similarity while taking care of case when dividend is 0!
distance = (
( sa.size || sb.size ) ?
1 - ( intersectSize / ( sa.size + sb.size - intersectSize ) ) :
0
);
return distance;
}; // jaccard()
// Export Jaccard.
module.exports = jaccard;