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6/30/2020
Analytics/despiking.js at master · oluwafemi2016/Analytics · GitHub
oluwafemi2016 / Analytics
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master
Analytics / despiking.js /
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//DESPIKE
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//1. This functions removes outliers from a 1D dataset
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//2. The cut-offs are: low outliers => beneath first quartile and high outliers => above third qua
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//3. Replaces outliers with linear interpolation of neighboring non-outliers
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//Required Dependency
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const outliers = require("outliers");
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function despike(array) {
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//Clean dirty array
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const array_clean = [];
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array.forEach((val) => {
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if (!isNaN(val)) {
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array_clean.push(val);
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}
});
https://github.com/oluwafemi2016/Analytics/blob/master/despiking.js
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6/30/2020
Analytics/despiking.js at master · oluwafemi2016/Analytics · GitHub
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console.log("array_clean", array_clean)
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//Remove Outliers from cleaned array
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const array_filtered = array_clean.filter(outliers());
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console.log("array_filtered", array_filtered, array_filtered.length)
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//Next: linearly interpolate between neighboring elements to fill in the space of outliers
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//Get outliers
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const outlier = outliers(array_clean);
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console.log("outliers", outlier)
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//Get indices of outliers in array_clean
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const Index_outliers = [];
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for (let j = 0; j < outlier.length; j++) {
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Index_outliers.push(array_clean.indexOf(outlier[j]));
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}
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console.log("Index_Outliers", Index_outliers)
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//Splice into array_clean_filtered the interpolated values of neighbors to outliers
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//Caveat: if one of the neighbors is undefined/especially at edges/ends, then pick a non-NaN n
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const interp = [];
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for (let j = 0; j < Index_outliers.length; j++) {
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if (Index_outliers[j] == 0) {
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interp[j] = array_clean[1];
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} else if (Index_outliers[j] == array_clean.length - 1) {
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interp[j] = array_clean[array_clean.length - 2];
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} else {
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interp[j] = (array_clean[Index_outliers[j] - 1] + array_clean[Index_outliers[j] + 1])
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}
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array_filtered.splice(Index_outliers[j], 0, interp[j]);
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}
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console.log("interp", interp)
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console.log("array_filtered 2", array_filtered)
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//Get Indices of all NaN elements in dirty array
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const Index_NaN = [];
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array.filter(function (arr, indx) {
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if (isNaN(arr)) {
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Index_NaN.push(indx)
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}
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});
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console.log("Index_NaN", Index_NaN)
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//With the known Index substitute/splice the NaNs into array filtered
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for (let j = 0; j < Index_NaN.length; j++) {
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array_filtered.splice(Index_NaN[j], 0, NaN);
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}
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const despiked_array = array_filtered;
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return (despiked_array)
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}
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//Testing Only
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const A = [NaN, -120, 14, 12.5, NaN, 50, 13, 1400, 16, 18.6, -600, 65, 66, 1200, NaN, NaN]
https://github.com/oluwafemi2016/Analytics/blob/master/despiking.js
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6/30/2020
Analytics/despiking.js at master · oluwafemi2016/Analytics · GitHub
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const desp = despike(A);
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console.log("desp", desp);
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//console.log("outliers", outliers(A))
https://github.com/oluwafemi2016/Analytics/blob/master/despiking.js
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