function determineMeanAndStddev(data) {
  const dataMean = data.mean(0);
  // TODO(bileschi): Simplify when and if tf.var / tf.std added to the API.
  const diffFromMean = data.sub(dataMean);
  const squaredDiffFromMean = diffFromMean.square();
  const variance = squaredDiffFromMean.mean(0);
  const dataStd = variance.sqrt();
  return {dataMean, dataStd};
}
Calculates the mean and standard deviation of each column of a data array.

@param {Tensor2d} data Dataset from which to calculate the mean and
                       std of each column independently.

@returns {Object} Contains the mean and standard deviation of each vector
                  column as 1d tensors.