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| 1 | +/** |
| 2 | +* @license Apache-2.0 |
| 3 | +* |
| 4 | +* Copyright (c) 2018 The Stdlib Authors. |
| 5 | +* |
| 6 | +* Licensed under the Apache License, Version 2.0 (the "License"); |
| 7 | +* you may not use this file except in compliance with the License. |
| 8 | +* You may obtain a copy of the License at |
| 9 | +* |
| 10 | +* http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | +* |
| 12 | +* Unless required by applicable law or agreed to in writing, software |
| 13 | +* distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | +* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | +* See the License for the specific language governing permissions and |
| 16 | +* limitations under the License. |
| 17 | +*/ |
| 18 | + |
| 19 | +'use strict'; |
| 20 | + |
| 21 | +// MODULES // |
| 22 | + |
| 23 | +var PINF = require( '@stdlib/constants/float64/pinf' ); |
| 24 | +var NINF = require( '@stdlib/constants/float64/ninf' ); |
| 25 | +var isnan = require( '@stdlib/math/base/assert/is-nan' ); |
| 26 | + |
| 27 | + |
| 28 | +// MAIN // |
| 29 | + |
| 30 | +/** |
| 31 | +* Returns an accumulator function which incrementally computes a range while ignoring NaN values. |
| 32 | +* |
| 33 | +* @returns {Function} accumulator function |
| 34 | +* |
| 35 | +* @example |
| 36 | +* var accumulator = incrnanrange(); |
| 37 | +* |
| 38 | +* var range = accumulator(); |
| 39 | +* // returns null |
| 40 | +* |
| 41 | +* range = accumulator( 3.14 ); |
| 42 | +* // returns 0.0 |
| 43 | +* |
| 44 | +* range = accumulator( NaN ); |
| 45 | +* // returns 0.0 |
| 46 | +* |
| 47 | +* range = accumulator( -5.0 ); |
| 48 | +* // returns 8.14 |
| 49 | +* |
| 50 | +* range = accumulator( 10.1 ); |
| 51 | +* // returns 15.1 |
| 52 | +* |
| 53 | +* range = accumulator(); |
| 54 | +* // returns 15.1 |
| 55 | +*/ |
| 56 | +function incrnanrange() { |
| 57 | + var range; |
| 58 | + var max = NINF; |
| 59 | + var min = PINF; |
| 60 | + |
| 61 | + return accumulator; |
| 62 | + |
| 63 | + /** |
| 64 | + * If provided a value, the accumulator function returns an updated range while ignoring NaN values. If not provided a value, the accumulator function returns the current range. |
| 65 | + * |
| 66 | + * @private |
| 67 | + * @param {number} [x] - new value |
| 68 | + * @returns {(number|null)} range or null |
| 69 | + */ |
| 70 | + function accumulator( x ) { |
| 71 | + if ( arguments.length === 0 ) { |
| 72 | + return ( range === void 0 ) ? null : range; |
| 73 | + } |
| 74 | + if ( isnan( x ) ) { |
| 75 | + return range; |
| 76 | + } |
| 77 | + if ( x > max ) { |
| 78 | + max = x; |
| 79 | + } |
| 80 | + if ( x < min ) { |
| 81 | + min = x; |
| 82 | + } |
| 83 | + range = max - min; |
| 84 | + return range; |
| 85 | + } |
| 86 | +} |
| 87 | + |
| 88 | + |
| 89 | +// EXPORTS // |
| 90 | + |
| 91 | +module.exports = incrnanrange; |
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