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54 lines
1.4 KiB
54 lines
1.4 KiB
4 months ago
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import { Base } from './base';
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import { Domain, ThresholdOptions, Range } from '../types';
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import { bisect, isValid } from '../utils';
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/**
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* 将连续的定义域分段，每一段所有的值对应离散的值域中一个值
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*/
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export class Threshold<O extends ThresholdOptions = ThresholdOptions> extends Base<O> {
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/** threshold 的数量 */
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protected n: number;
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protected thresholds: number[];
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protected getDefaultOptions() {
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return {
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domain: [0.5],
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range: [0, 1],
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} as O;
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}
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constructor(options?: ThresholdOptions) {
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super(options as O);
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}
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/**
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* 二分查找到输入值在哪一段，返回对应的值域中的值
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*/
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public map(x: Domain<ThresholdOptions>) {
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if (!isValid(x)) return this.options.unknown;
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const index = bisect(this.thresholds, x, 0, this.n);
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return this.options.range[index];
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}
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/**
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* 在值域中找到对应的值，并返回在定义域中属于哪一段
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*/
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public invert(y: Range<ThresholdOptions>) {
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const { range } = this.options;
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const index = range.indexOf(y);
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const domain = this.thresholds;
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return [domain[index - 1], domain[index]];
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}
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public clone() {
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return new Threshold<O>(this.options);
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}
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protected rescale() {
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const { domain, range } = this.options;
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this.n = Math.min(domain.length, range.length - 1);
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this.thresholds = domain;
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}
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}
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