function getShortColumn(positions, buffer) {
  const minPosition = arrayMin(positions);
  for (let i = 0, len = positions.length; i < len; i++) {
    if (positions[i] >= minPosition - buffer && positions[i] <= minPosition + buffer) {
      return i;
    }
  }

  return 0;
}
Find index of short column, the first from the left where this item will go.

@param {Array.<number>} positions The array to search for the smallest number.
@param {number} buffer Optional buffer which is very useful when the height
    is a percentage of the width.
@return {number} Index of the short column.