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23 lines
697 B
JavaScript
23 lines
697 B
JavaScript
// jshint esversion: 6
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// Substitute for a d3 linear scale - less flexible, more performant.
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// Returns a function which will scale a value.
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//
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// Example will scale [0,1] to [-1,1]
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// var myScale = scaleLinear([0, 1], [-1, 1]);
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// myScale(0) === -1
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// this is is equivalent to d3.scaleLinear().domain([0,1]).range([-1,1])
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export default (domain, range) => {
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const domainStart = domain[0];
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const scale = (range[1] - range[0]) / (domain[1] - domain[0]);
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const invScale = 1 / scale;
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const rangeStart = range[0];
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const f = (value) => (value - domainStart) * scale + rangeStart;
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// inverter
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f.invert = (value) => (value - rangeStart) * invScale + domainStart;
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return f;
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};
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