model_selection.train_test_split

import { train_test_split } from 'machinelearn/model_selection';

const X = [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9]];
const y = [0, 1, 2, 3, 4];

train_test_split(X, y, {
  test_size: 0.33,
  train_size: 0.67,
  random_state: 42
});

/*
* { xTest: [ [ 0, 1 ], [ 8, 9 ] ],
*  xTrain: [ [ 4, 5 ], [ 6, 7 ], [ 2, 3 ] ],
*  yTest: [ 0, 4 ],
*  yTrain: [ 2, 3, 1 ] }