KNN algorithm by lodash

knn.js

const outputs = [
  [10, .5, 16, 1],
  [200, .5, 16, 4],
  [350, .5, 16, 4],
  [600, .5, 16, 5],
]

const predictionPoint = 300;
const k = 3

function distance(point) {
	return Math.abs(point - predictionPoint)
}

_.chain(outputs)
  .map(row => [distance(row[0]), row[3]])
  .sortBy(row => row[0])
  .slice(0, k)
  .countBy(row => row[1])
  .toPairs()
  .sortBy(row => row[1])
  .last()
  .first()
  .parseInt()
  .value()