Created
October 19, 2015 07:13
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d3-random using ramdajs
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| import R from 'ramda'; | |
| const rRandom = (x = Math.random() * 2 - 1, y = Math.random() * 2 - 1) => { | |
| const r = x * x + y * y; | |
| if (!r || r > 1) return rRandom(); | |
| else return { x: x, r: r }; | |
| } | |
| const normal = (µ = 0, σ = 1) => { | |
| const rr = rRandom(); | |
| return µ + σ * rr.x * Math.sqrt(-2 * Math.log(rr.r) / rr.r); | |
| }; | |
| const logNormal = R.compose(Math.exp, normal); | |
| const irwinHall = R.compose( | |
| R.reduce((a, b) => (a + b), 0), | |
| R.times(() => Math.random()) | |
| ); | |
| const bates = m => irwinHall(m) / m; | |
| export default { | |
| normal: R.curry(normal), | |
| logNormal: R.curry(logNormal), | |
| irwinHall: R.curry(irwinHall), | |
| bates: R.curry(bates) | |
| } |
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