[SPARK-9788] LDA docConcentration, gammaShape 1.5 binary incompatibility fixes

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.5.0
• Component/s: MLlib
• Target Version/s: 1.5.0
• Assignee: Feynman Liang
• Reporter: Joseph K. Bradley
• Shepherd: Joseph K. Bradley
• Created: 10/Aug/15 18:46
• Updated: 11/Aug/15 21:22
• Resolved: 11/Aug/15 21:22

Description

From SPARK-9658:

1. LDA.docConcentration

It will be nice to keep the old APIs unchanged. Proposal:

• Add “asymmetricDocConcentration” and revert docConcentration changes.
• If the (internal) doc concentration vector is a single value, “getDocConcentration" returns it. If it is a constant vector, getDocConcentration returns the first item, and fails otherwise.

2. LDAModel.gammaShape

This should be given a default value.

Issue Links

• relates to: SPARK-9658 ML 1.5 QA: API: Binary incompatible changes
• links to: [Github] Pull Request #8077 (feynmanliang)