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https://issues.apache.org/jira/browse/MADLIB-1168?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16321258#comment-16321258
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ASF GitHub Bot commented on MADLIB-1168:
----------------------------------------

GitHub user Swatisoni opened a pull request:

    https://github.com/apache/madlib/pull/223

    Balance datasets : re-sampling technique

    JIRA:MADLIB-1168
    
    Additional Authors:
    Orhan Kislal [email protected]
    Jingyi Mei [email protected]
    
    Balanced datasets Phase 1 and Phase 2 implementation which performs 
balanced sampling in following specified re-sampling techniques
            1. Under-sampling the majority class(es), with- and without 
replacement
            2. Over-sampling the minority class
            3. Combining over- and under-sampling
                -  Uniform sampling of all classes (default case)
        4. Create ensemble balanced sets
                - Re-sampling given comma-delimited string of specific class 
and respective sample sizes
            5. IC tests
    
    Balanced sampling with grouping functionality will be implemented in phase 3

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/Swatisoni/madlib balanced_sets_final

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/madlib/pull/223.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #223
    
----
commit 3b2d1f18b9cf5ef8f78669678d82dc29cd11812b
Author: Swatisoni <soniswati.2010@...>
Date:   2018-01-10T20:07:36Z

    Balance datasets : re-sampling technique
    
    JIRA:MADLIB-1168
    
    Additional Authors:
    Orhan Kislal [email protected]
    Jingyi Mei [email protected]
    
    Balanced datasets Phase 1 and Phase 2 implementation which performs 
balanced sampling in following specified re-sampling techniques
            1. Under-sampling the majority class(es), with- and without 
replacement
            2. Over-sampling the minority class
            3. Combining over- and under-sampling
                -  Uniform sampling of all classes (default case)
        4. Create ensemble balanced sets
                - Re-sampling given comma-delimited string of specific class 
and respective sample sizes
            5. IC tests
    
    Balanced sampling with grouping functionality will be implemented in phase 3

----


> Balance datasets
> ----------------
>
>                 Key: MADLIB-1168
>                 URL: https://issues.apache.org/jira/browse/MADLIB-1168
>             Project: Apache MADlib
>          Issue Type: New Feature
>          Components: Module: Sampling
>            Reporter: Frank McQuillan
>            Assignee: ssoni
>             Fix For: v1.14
>
>         Attachments: MADlib Balance Datasets Requirements.pdf, 
> MADlib_Balance_Datasets_Requirements_v2.pdf
>
>
> From [1] here is the motivation behind balancing datasets:
> “Most classification algorithms will only perform optimally when the number 
> of samples of each class is roughly the same. Highly skewed datasets, where 
> the minority is heavily outnumbered by one or more classes, have proven to be 
> a challenge while at the same time becoming more and more common.
> One way of addressing this issue is by re-sampling the dataset as to offset 
> this imbalance with the hope of arriving at a more robust and fair decision 
> boundary than you would otherwise.
> Re-sampling techniques can be divided in these categories:
> * Under-sampling the majority class(es).
> * Over-sampling the minority class.
> * Combining over- and under-sampling.
> * Create ensemble balanced sets.”
> There is an extensive literature on balancing datasets.  The plan for MADlib 
> in the initial phase is to offer basic functionality that can be extended in 
> later phases based on feedback from users.  
> Please see attached document for proposed scope of this story.
> References
> [1] imbalance-learn Python project
> http://contrib.scikit-learn.org/imbalanced-learn/stable/index.html
> https://github.com/scikit-learn-contrib/imbalanced-learn



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