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Random Sampling

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Get a sample(random subarray) from array


function samplesub(arr, size)
{
  var shuffled = arr.slice(0), i = arr.length, min = i - size, temp, index;
  while (i-- > min)
  {
    index = Math.floor((i + 1) * Math.random());
    temp = shuffled[index];
    shuffled[index] = shuffled[i];
    shuffled[i] = temp;
  }
  return shuffled.slice(min);
}

function sample(arr, size)
{
  var shuffled = arr.slice(0), i = arr.length, temp, index;
  while (i--)
  {
    index = Math.floor((i + 1) * Math.random());
    temp = shuffled[index];
    shuffled[index] = shuffled[i];
    shuffled[i] = temp;
  }
  return shuffled.slice(0, size);
}