Nostradamus.js

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$3

$3

$3

$3

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$ npm install nostradamus

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Option 1:

// plain-vanilla
var forecast = require('nostradamus')
, data = [
362, 385, 432, 341, 382, 409,
498, 387, 473, 513, 582, 474,
544, 582, 681, 557, 628, 707,
773, 592, 627, 725, 854, 661
]
, alpha = 0.5 // overall smoothing component
, beta = 0.4 // trend smoothing component
, gamma = 0.6 // seasonal smoothing component
, period = 4 // # of observations per season
, m = 4 // # of future observations to forecast
, predictions = [];

predictions = forecast(data, alpha, beta, gamma, period, m);
// -> [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 594.8043646513713, 357.12171044215734, …]

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Option 2:

// faster w/ reuse of internal arrays
// if you know you'll be feeding it
// the same # of data, same params (alpha, beta, etc.),
// and you need to throw tons of data at it

var setupForecast = require('nostradamus').memo // note the (dot)memo
, forecast
, data = [
362, 385, 432, 341, 382, 409,
498, 387, 473, 513, 582, 474,
544, 582, 681, 557, 628, 707,
773, 592, 627, 725, 854, 661
]
, predictions = [];

forecast = setupForecast({
length: data.length,
alpha: 0.5, // overall smoothing component
beta: 0.4, // trend smoothing component
gamma: 0.6, // seasonal smoothing component
period: 4, // # of observations per season
m: 4 // # of future observations to forecase
});

predictions = forecast(data);
// -> [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 594.8043646513713, 357.12171044215734, …]

forecast([…]);
forecast([…]);
forecast([…]);
…

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Some rules your parameters must abide by:
- alpha >= 0.0 && alpha >= 1.0
- beta >= 0.0 && beta <= 1.0
- gamma >= 0.0 && gamma <= 1.0
- m > 0
- m <= period

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This project would't exist, if not for the versions written in Go and Java. Thanks!