[HIVEMALL-234] Fix mismatched default value between EtaEstimator and UDF option description

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.5.0, 0.5.2
• Fix Version/s: 0.6.0
• Assignee: Takuya Kitazawa
• Reporter: Takuya Kitazawa
• Created: 23/Jan/19 07:42
• Updated: 30/Jan/19 05:02
• Resolved: 30/Jan/19 05:02

Description

UDF option description sometimes tells a lie:

• `train_mf_sgd` says default value of `eta0` is 0.2: https://github.com/apache/incubator-hivemall/blob/7b61a3be8178fef40154f4009fef2989a9fd4c49/core/src/main/java/hivemall/mf/MatrixFactorizationSGDUDTF.java#L44
• But `EtaEstimator` actually uses 0.1 as a default value: https://github.com/apache/incubator-hivemall/blob/31932fd7c63f9bb21eba8959944d03f280b6deb9/core/src/main/java/hivemall/optimizer/EtaEstimator.java#L153

In order to avoid those mismatched cases, define EtaEstimator's default values as constants, and directly refer them from `getOptions`.

Issue Links

• links to: GitHub Pull Request #179