Minor Description
ml.classification.ClassificationModel will ignore empty output columns.
However, OneVsRestModel still try to append new column even if its name is an empty string.
scala> ovrModel.setPredictionCol("").transform(test).show
+-----+--------------------+--------------------+---+
|label| features| rawPrediction| |
+-----+--------------------+--------------------+---+
| 0.0|(4,[0,1,2,3],[-0....|[-0.0965652626152...|2.0|
| 0.0|(4,[0,1,2,3],[-0....|[0.07880609384635...|2.0|
| 0.0|(4,[0,1,2,3],[-1....|[0.01891571586984...|2.0|
| 0.0|(4,[0,1,2,3],[0.1...|[0.72409973016524...|0.0|
| 0.0|(4,[0,1,2,3],[0.1...|[0.48045978946729...|2.0|
| 0.0|(4,[0,1,2,3],[0.3...|[1.05496616040758...|0.0|
| 0.0|(4,[0,1,2,3],[0.3...|[0.79508659065535...|0.0|
| 0.0|(4,[0,1,2,3],[0.6...|[1.47437469552081...|0.0|
| 0.0|(4,[0,1,2,3],[0.6...|[1.23302929670223...|0.0|
| 0.0|(4,[0,1,2,3],[0.8...|[1.79816156359706...|0.0|
| 1.0|(4,[0,1,2,3],[-0....|[-3.1564309664080...|1.0|
| 1.0|(4,[0,1,2,3],[-0....|[-3.2217906250571...|1.0|
| 1.0|(4,[0,1,2,3],[-0....|[-2.9171126308553...|1.0|
| 1.0|(4,[0,1,2,3],[-0....|[-2.8316993051998...|1.0|
| 2.0|(4,[0,1,2,3],[-0....|[-1.6486206847760...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-0.9252139721697...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-0.9025379528484...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-0.8518243169707...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-1.0990190524225...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-0.9973479746889...|2.0|
+-----+--------------------+--------------------+---+
only showing top 20 rows
scala> ovrModel.setPredictionCol("").setRawPredictionCol("raw").transform(test).show
+-----+--------------------+--------------------+---+
|label| features| raw| |
+-----+--------------------+--------------------+---+
| 0.0|(4,[0,1,2,3],[-0....|[-0.0965652626152...|2.0|
| 0.0|(4,[0,1,2,3],[-0....|[0.07880609384635...|2.0|
| 0.0|(4,[0,1,2,3],[-1....|[0.01891571586984...|2.0|
| 0.0|(4,[0,1,2,3],[0.1...|[0.72409973016524...|0.0|
| 0.0|(4,[0,1,2,3],[0.1...|[0.48045978946729...|2.0|
| 0.0|(4,[0,1,2,3],[0.3...|[1.05496616040758...|0.0|
| 0.0|(4,[0,1,2,3],[0.3...|[0.79508659065535...|0.0|
| 0.0|(4,[0,1,2,3],[0.6...|[1.47437469552081...|0.0|
| 0.0|(4,[0,1,2,3],[0.6...|[1.23302929670223...|0.0|
| 0.0|(4,[0,1,2,3],[0.8...|[1.79816156359706...|0.0|
| 1.0|(4,[0,1,2,3],[-0....|[-3.1564309664080...|1.0|
| 1.0|(4,[0,1,2,3],[-0....|[-3.2217906250571...|1.0|
| 1.0|(4,[0,1,2,3],[-0....|[-2.9171126308553...|1.0|
| 1.0|(4,[0,1,2,3],[-0....|[-2.8316993051998...|1.0|
| 2.0|(4,[0,1,2,3],[-0....|[-1.6486206847760...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-0.9252139721697...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-0.9025379528484...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-0.8518243169707...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-1.0990190524225...|2.0|
| 2.0|(4,[0,1,2,3],[-0....|[-0.9973479746889...|2.0|
+-----+--------------------+--------------------+---+
only showing top 20 rows
