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20 lines
755 B
JavaScript
20 lines
755 B
JavaScript
export async function createStreamVisualizer(stream, { maxPoints, alpha, width, height, yDomain }) {
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const d3 = await import('d3');
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const data = [];
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let ema = null;
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for await (const { timestamp, value } of stream) {
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ema = ema === null ? value : alpha * value + (1 - alpha) * ema;
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data.push({ timestamp, value, ema });
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if (data.length > maxPoints) data.shift();
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}
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if (!data.length) return { data, path: '' };
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const x = d3.scaleLinear().domain([data[0].timestamp, data[data.length - 1].timestamp]).range([0, width]);
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const y = d3.scaleLinear().domain(yDomain).range([height, 0]);
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const path = d3.line().x(d => x(d.timestamp)).y(d => y(d.ema))(data);
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return { data, path };
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}
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export default createStreamVisualizer; |