@Test
void asDoubleColumn() {

  String[] words = {"foo", "bar", "larry", "foo", "lion", "ben", "tiger", "bar"};
  StringColumn wordColumn = StringColumn.create("words", words);
  DoubleColumn result = wordColumn.asDoubleColumn();
  assertArrayEquals(
      new double[] {0.0, 1.0, 2.0, 0.0, 3.0, 4.0, 5.0, 1.0}, result.asDoubleArray(), 0.000_000_1);
}