[jira] [Closed] (MADLIB-1240) Vector to Columns

["Frank McQuillan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MADLIB-1240?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Frank McQuillan closed MADLIB-1240.
-----------------------------------
    Resolution: Fixed

> Vector to Columns
> -----------------
>
>                 Key: MADLIB-1240
>                 URL: https://issues.apache.org/jira/browse/MADLIB-1240
>             Project: Apache MADlib
>          Issue Type: New Feature
>          Components: Module: Utilities
>            Reporter: Frank McQuillan
>            Assignee: Nandish Jayaram
>            Priority: Major
>             Fix For: v1.15
>
>
> related to https://issues.apache.org/jira/browse/MADLIB-1239
> Vector to Columns
> Converts a feature array in a single column of an output table into multiple columns.  This process can be used to reverse the function cols2vec.
> {code}
> vec2cols(
>     source_table,
>     out_table,
>     vector_col,
>     feature_names,
>     cols_to_output
>     )
> source_table
> TEXT. Name of the table containing the source data.
> out_table
> TEXT. Name of the generated table containing the output. If a table with the same name already exists, an error will be returned. 
> vector_col
> TEXT.  Name of the column containing the feature array.  Must be a one-dimensional array.
> feature_names (optional)
> TEXT[]. Array of names associated with the feature array.  Note that this array exists in the summary table created by the function 'cols2vec'.  If the feature_names array is not specified, column names will be automatically generated of the form 'f1, f2, ...fn'
> cols_to_output (optional)
> TEXT, default NULL. Comma-separated string of column names from the source table to keep in the output table, in addition to the feature columns.  To keep all columns from the source table, use '*'.
> Output
> The output table produced by the vec2cols function contains the following columns:
> <...>
> Columns from source table, depending on which ones are kept (if any).
> feature columns
> Columns for each of the features in 'vector_col'.  Column type will depend on the feature array type in the source table.  Column naming will depend on whether the parameter 'feature_names' is used.
> {code}
> Notes
> (1)
> The function
> http://pivotalsoftware.github.io/PDLTools/group__ArrayUtilities.html
> is similar but the proposed MADlib one has more options.  To do the equivalent of the PDL Tools one in MADlib, you would do:
> {code}
> vec2cols(
>     table_name,
>     output_table,
>     vector_column,
>     NULL,
>     '*'
>     )
> {code}
> (2)
> Please put the generated feature columns on the right side of the output table, i.e., they will be the last column on the right.  Maintain the order of the array.
> Examples of feature name usage
> {code}
> select vec2cols(
> source_table,
> out_table,
> vector_col,
> SELECT col_names FROM a_table,  -- feature name array exists in table 'a_table'
> cols_to_output
> )
> {code}
> OR 
> {code}
> select vec2cols(
> source_table,
> out_table,
> vector_col,
> dictionary,
> cols_to_output
> ) from (select col_names as feature_names from a_table) q -- feature names array exists in table 'a_table'
> {code}
> OR
> {code}
> select vec2cols(
> source_table,
> out_table,
> vector_col,
> {'n1', 'n2'... 'nn'}, -- user explicitly enters feature names 
> cols_to_output
> )
> {code}
> OR
> {code}
> select vec2cols(
> source_table,
> out_table,
> vector_col,
> NULL, -- no dictionary exists, will auto-generate column names as f1, f2, ...
> cols_to_output
> )
> {code}



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