0675dd924d
Reviewed By: passy Differential Revision: D17863711 fbshipit-source-id: 259dc77826fb803ff1b88c88529d7f679d3b74d8
62 lines
1.4 KiB
TypeScript
62 lines
1.4 KiB
TypeScript
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @format
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*/
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export default class LowPassFilter {
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constructor(smoothing: number = 0.9) {
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this.smoothing = smoothing;
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this.buffer = [];
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this.bufferMaxSize = 5;
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}
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bufferMaxSize: number;
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smoothing: number;
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buffer: Array<number>;
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hasFullBuffer(): boolean {
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return this.buffer.length === this.bufferMaxSize;
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}
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push(value: number): number {
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let removed: number = 0;
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if (this.hasFullBuffer()) {
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const tmp: number | undefined = this.buffer.shift();
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if (tmp === undefined) {
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throw new Error(
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'Invariant violation: Buffer reported full but shift returned nothing.',
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);
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}
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removed = tmp;
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}
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this.buffer.push(value);
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return removed;
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}
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next(nextValue: number): number {
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// push new value to the end, and remove oldest one
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const removed = this.push(nextValue);
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// smooth value using all values from buffer
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const result = this.buffer.reduce(this._nextReduce, removed);
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// replace smoothed value
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this.buffer[this.buffer.length - 1] = result;
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return result;
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}
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_nextReduce = (last: number, current: number): number => {
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return this.smoothing * current + (1 - this.smoothing) * last;
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};
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}
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