// StringIndexer define new 'label' column with 'result' column
val indexer = new StringIndexer()
  .setInputCol("creditability")
  .setOutputCol("label")
val labelDf = indexer.fit(featureDf).transform(featureDf)
labelDf.printSchema()
/*
 * outout
root
 |-- creditability: double (nullable = true)
 |-- balance: double (nullable = true)
 |-- duration: integer (nullable = true)
 |-- history: integer (nullable = true)
 |-- purpose: integer (nullable = true)
 |-- amount: integer (nullable = true)
 |-- savings: integer (nullable = true)
 |-- employment: integer (nullable = true)
 |-- instPercent: integer (nullable = true)
 |-- sexMarried: integer (nullable = true)
 |-- guarantors: integer (nullable = true)
 |-- residenceDuration: integer (nullable = true)
 |-- assets: integer (nullable = true)
 |-- age: integer (nullable = true)
 |-- concCredit: integer (nullable = true)
 |-- apartment: integer (nullable = true)
 |-- credits: integer (nullable = true)
 |-- occupation: integer (nullable = true)
 |-- dependents: integer (nullable = true)
 |-- hasPhone: integer (nullable = true)
 |-- foreign: integer (nullable = true)
 |-- features: vector (nullable = true)
 |-- label: double (nullable = false)
*/

labelDf.show(10)
/*
 * outout
+-------------+-------+--------+-------+-------+------+-------+----------+-----------+----------+----------+-----------------+------+---+----------+---------+-------+----------+----------+--------+-------+--------------------+-----+
|creditability|balance|duration|history|purpose|amount|savings|employment|instPercent|sexMarried|guarantors|residenceDuration|assets|age|concCredit|apartment|credits|occupation|dependents|hasPhone|foreign|            features|label|
+-------------+-------+--------+-------+-------+------+-------+----------+-----------+----------+----------+-----------------+------+---+----------+---------+-------+----------+----------+--------+-------+--------------------+-----+
|          1.0|    1.0|       9|      4|      0|  2799|      1|         3|          2|         3|         1|                2|     1| 36|         3|        1|      2|         3|         2|       1|      1|[1.0,9.0,4.0,0.0,...|  0.0|
|          1.0|    2.0|      12|      2|      9|   841|      2|         4|          2|         2|         1|                4|     1| 23|         3|        1|      1|         2|         1|       1|      1|[2.0,12.0,2.0,9.0...|  0.0|
|          1.0|    1.0|      12|      4|      0|  2122|      1|         3|          3|         3|         1|                2|     1| 39|         3|        1|      2|         2|         2|       1|      2|[1.0,12.0,4.0,0.0...|  0.0|
|          1.0|    1.0|      12|      4|      0|  2171|      1|         3|          4|         3|         1|                4|     2| 38|         1|        2|      2|         2|         1|       1|      2|[1.0,12.0,4.0,0.0...|  0.0|
|          1.0|    1.0|      10|      4|      0|  2241|      1|         2|          1|         3|         1|                3|     1| 48|         3|        1|      2|         2|         2|       1|      2|[1.0,10.0,4.0,0.0...|  0.0|
|          1.0|    1.0|       8|      4|      0|  3398|      1|         4|          1|         3|         1|                4|     1| 39|         3|        2|      2|         2|         1|       1|      2|[1.0,8.0,4.0,0.0,...|  0.0|
|          1.0|    1.0|       6|      4|      0|  1361|      1|         2|          2|         3|         1|                4|     1| 40|         3|        2|      1|         2|         2|       1|      2|[1.0,6.0,4.0,0.0,...|  0.0|
|          1.0|    4.0|      18|      4|      3|  1098|      1|         1|          4|         2|         1|                4|     3| 65|         3|        2|      2|         1|         1|       1|      1|[4.0,18.0,4.0,3.0...|  0.0|
|          1.0|    2.0|      24|      2|      3|  3758|      3|         1|          1|         2|         1|                4|     4| 23|         3|        1|      1|         1|         1|       1|      1|[2.0,24.0,2.0,3.0...|  0.0|
|          1.0|    1.0|      11|      4|      0|  3905|      1|         3|          2|         3|         1|                2|     1| 36|         3|        1|      2|         3|         2|       1|      1|[1.0,11.0,4.0,0.0...|  0.0|
+-------------+-------+--------+-------+-------+------+-------+----------+-----------+----------+----------+-----------------+------+---+----------+---------+-------+----------+----------+--------+-------+--------------------+-----+
*/