zhengruifeng created SPARK-17057:
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Summary: ProbabilisticClassifierModels' prediction more reasonable
with multi zero thresholds
Key: SPARK-17057
URL: https://issues.apache.org/jira/browse/SPARK-17057
Project: Spark
Issue Type: Improvement
Components: ML
Reporter: zhengruifeng
{code}
val path = "./data/mllib/sample_multiclass_classification_data.txt"
val data = spark.read.format("libsvm").load(path)
val rfm = rf.fit(data)
scala> rfm.setThresholds(Array(0.0,0.0,0.0))
res4: org.apache.spark.ml.classification.RandomForestClassificationModel =
RandomForestClassificationModel (uid=rfc_cbe640b0eccc) with 20 trees
scala> rfm.transform(data).show(5)
+-----+--------------------+--------------+-------------+----------+
|label| features| rawPrediction| probability|prediction|
+-----+--------------------+--------------+-------------+----------+
| 1.0|(4,[0,1,2,3],[-0....|[0.0,20.0,0.0]|[0.0,1.0,0.0]| 0.0|
| 1.0|(4,[0,1,2,3],[-0....|[0.0,20.0,0.0]|[0.0,1.0,0.0]| 0.0|
| 1.0|(4,[0,1,2,3],[-0....|[0.0,20.0,0.0]|[0.0,1.0,0.0]| 0.0|
| 1.0|(4,[0,1,2,3],[-0....|[0.0,20.0,0.0]|[0.0,1.0,0.0]| 0.0|
| 0.0|(4,[0,1,2,3],[0.1...|[20.0,0.0,0.0]|[1.0,0.0,0.0]| 0.0|
+-----+--------------------+--------------+-------------+----------+
only showing top 5 rows
{code}
If multi thresholds are set zero, the prediction of
{{ProbabilisticClassificationModel}} is the first index whose corresponding
threshold is 0.
However, in this case, the index with max {{probability}} among indices with
0-threshold should be more reasonable to mark as
{{prediction}}.
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