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add-noise.js
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add-noise.js
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var _ = require("underscore");
var randgen = require("randgen");
function scale_magnitude(pairs)
{
var scaled = [];
// Gaussian scale the magnitudes
_.each(pairs, function(pair) {
var magnitude = pair[0];
var scaling_factor = pair[1];
scaled.push(Math.max(Math.min(magnitude * scaling_factor, 1.0), 0.0)); // constrain to [0.0, 1.0]
});
return scaled;
}
function scale_list(triples, pairs) {
var scaled = scale_magnitude(pairs);
for (var i=2;i<triples.length;i+=3) {
triples[i] = scaled[(i-2)/3];
}
}
function scale(triples, mean, standard_deviation) {
// Extract every third value, which leaves the latitude and longitude but
// takes the magnitude.
var magnitudes = triples.filter(function(_,i){ return (i+1)%3 == 0});
var scaling_factors = randgen.rvnorm(magnitudes.length, mean, standard_deviation);
var pairs = _.zip(magnitudes, scaling_factors);
return scale_list(triples, pairs);
}
exports.scale_magnitude = scale_magnitude;
exports.scale_list = scale_list;
exports.scale = scale;