code: public Table sampleX(double proportion) {
          Preconditions.checkArgument(proportion <= 1 && proportion >= 0,
                  "The sample proportion must be between 0 and 1");
  
          int tableSize = (int) Math.round(rowCount() * proportion);
          return where(selectNRowsAtRandom(tableSize, rowCount()));
      }
docs: Returns a table consisting of randomly selected records from this table. The sample size is based on the
  given proportion
  
  @param proportion The proportion to go in the sample