83 lines
2.1 KiB
JavaScript
83 lines
2.1 KiB
JavaScript
|
/**
|
||
|
|
* @license Apache-2.0
|
||
|
|
*
|
||
|
|
* Copyright (c) 2018 The Stdlib Authors.
|
||
|
|
*
|
||
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
* you may not use this file except in compliance with the License.
|
||
|
|
* You may obtain a copy of the License at
|
||
|
|
*
|
||
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
*
|
||
|
|
* Unless required by applicable law or agreed to in writing, software
|
||
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
* See the License for the specific language governing permissions and
|
||
|
|
* limitations under the License.
|
||
|
|
*/
|
||
|
|
|
||
|
|
'use strict';
|
||
|
|
|
||
|
|
// VARIABLES //
|
||
|
|
|
||
|
|
var SORT_OPTS = {
|
||
|
|
'numeric': true // Use numeric collation such that "1" < "2" < "10"...
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
// FUNCTIONS //
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Comparator function to sort values in ascending order.
|
||
|
|
*
|
||
|
|
* @private
|
||
|
|
* @param {*} a - first value
|
||
|
|
* @param {*} b - second value
|
||
|
|
* @returns {number} negative number if `a` comes before `b, positive if `a` comes after `b`, and `0` if they are equivalent
|
||
|
|
*/
|
||
|
|
function ascending( a, b ) {
|
||
|
|
return String( a ).localeCompare( String( b ), void 0, SORT_OPTS );
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// MAIN //
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the unique elements in an array.
|
||
|
|
*
|
||
|
|
* @private
|
||
|
|
* @param {Array} arr - input array
|
||
|
|
* @returns {Array} array of unique elements
|
||
|
|
*/
|
||
|
|
function unique( arr ) {
|
||
|
|
var len;
|
||
|
|
var out;
|
||
|
|
var val;
|
||
|
|
var i;
|
||
|
|
var j;
|
||
|
|
|
||
|
|
// Copy the array to avoid mutation:
|
||
|
|
out = Array.prototype.slice.call( arr );
|
||
|
|
len = out.length;
|
||
|
|
|
||
|
|
// Sort array in ascending order:
|
||
|
|
out.sort( ascending );
|
||
|
|
|
||
|
|
// Loop through the array, only incrementing a pointer when successive values are different. When a succeeding value is different, move the pointer and set the next value. In the trivial case where all array elements are unique, we incur a slight penalty in resetting the element value for each unique value. In other cases, we simply move a unique value to a new position in the array. The end result is a sorted array with unique values.
|
||
|
|
for ( i = 1, j = 0; i < len; i++ ) {
|
||
|
|
val = out[ i ];
|
||
|
|
if ( out[ j ] !== val ) {
|
||
|
|
j += 1;
|
||
|
|
out[ j ] = val;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
// Truncate the array:
|
||
|
|
out.length = j+1;
|
||
|
|
return out;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// EXPORTS //
|
||
|
|
|
||
|
|
module.exports = unique;
|