[jira] [Closed] (MADLIB-1370) Knn - add zero check and output distance array

["Orhan Kislal (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MADLIB-1370?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Orhan Kislal closed MADLIB-1370.
--------------------------------

> Knn - add zero check and output distance array
> ----------------------------------------------
>
>                 Key: MADLIB-1370
>                 URL: https://issues.apache.org/jira/browse/MADLIB-1370
>             Project: Apache MADlib
>          Issue Type: Improvement
>          Components: k-NN
>            Reporter: Frank McQuillan
>            Assignee: Orhan Kislal
>            Priority: Minor
>             Fix For: v1.17
>
>
> In unsupervised mode of knn 
> http://madlib.apache.org/docs/latest/group__grp__knn.html
> when `point_source` and `test_source` are the same data set, nearest neighbors is not reliably returning the 0 distance point as a nearest neighbor.
> Could there a small neg issue here for a distance that is effectively 0 but shows up as neg epsilon?
> Also, please assess if we can add a vector of distances to the output file:
> {code}
> Output Format
> The output of the KNN module is a table with the following columns:
> id	INTEGER. The ids of test data points.
> test_column_name	DOUBLE PRECISION[]. The test data points.
> prediction	INTEGER. Label in case of classification, average value in case of regression.
> k_nearest_neighbours	INTEGER[]. List of nearest neighbors, sorted closest to furthest from the corresponding test point.
> distance DOUBLE PRECISION[].  Distance sorted in the same order as the 'k_nearest_neighbours' array.
> {code}



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