[MADLIB-1086] Unnest 2-D array by one level (i.e. into rows of 1-D arrays)

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: v1.11
• Component/s: Module: Utilities
• Assignee: Rashmi Raghu
• Reporter: Frank McQuillan
• Created: 31/Mar/17 20:20
• Updated: 27/Apr/17 22:26
• Resolved: 27/Apr/17 00:26

Description

Context

Currently k-means returns the following

centroids        | {{13.7533333333333,1.905,2.425,16.0666666666667,90.3333333333333,2.805,2.98,0.29,2.005,5.40663333333333,1.04166666666667, 3.31833333333333,1020.83333333333},
                   {14.255,1.9325,2.5025,16.05,110.5,3.055,2.9775,0.2975,1.845,6.2125,0.9975,3.365,1378.75}}
cluster_variance | {122999.110416013,30561.74805}
objective_fn     | 153560.858466013
frac_reassigned  | 0
num_iterations   | 3

Story

As a data scientist, I want to unnest 2-D array by one level (i.e. into rows of 1-D arrays) in K-means, so that I can get one centroid per row for follow on operations.

Acceptance

1) Add function to array operations
http://madlib.incubator.apache.org/docs/latest/group__grp__array.html
2) Add an example in k-means
http://madlib.incubator.apache.org/docs/latest/group__grp__kmeans.html
to demonstrate usage

Issue Links

• links to: GitHub Pull Request #116