Makoto YUI

Show better warning message when negative value is supplied for explanatory variable ``` Caused by: org.apache.hadoop.hive.ql.metadata.HiveException: java.lang.NegativeArraySizeException at hivemall.smile.classification.RandomForestClassifierUDTF.train(RandomForestClassifierUDTF.java:278) at hivemall.smile.classification.RandomForestClassifierUDTF.close(RandomForestClassifierUDTF.java:214) at org.apache.hadoop.hive.ql.exec.UDTFOperator.closeOp(UDTFOperator.java:145) at org.apache.hadoop.hive.ql.exec.Operator.close(Operator.java:616) at org.apache.hadoop.hive.ql.exec.Operator.close(Operator.java:630) at org.apache.hadoop.hive.ql.exec.Operator.close(Operator.java:630) at...

Need to know training option and diagnostics for debugging or for better understanding of prediction models.

http://arxiv.org/abs/1305.6646

- Refactor the base class of learners to be more easy to implement new algorithms for ML developers ObjectInspector should be transparent to ML implementation - Separate convex optimization algorithms...

http://en.wikipedia.org/wiki/Learning_to_rank

Improvements on Mix protocol

1

# ~~Fix MixServer to forgot models not being used~~ - Add a timer task to check obsolete sessions - The timer task iterates over MixServerHandler.groupMap to check obsolete entries -...

- Make tran() to return suffer loss - Show cumulative suffer loss in log on close()? - Suffer loss history server

## Dense2Sparse - Add dense2sparse() for converting dense matrix to sparse array - Add option flag to remove zero valued element or not ``` dense2sparse(array(array[1.0,2.0], array[0.0,4.0])) => array["1_1:1.0","1_2":2.0","2_2:4.0"] dense2sparse(array[1.0,2.0,0.0,4.0]) =>...

Normalized online learning, Ross+, '13 [[pdf](http://arxiv.org/pdf/1305.6646.pdf)]