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From "Terje Marthinussen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-1545) Add a bunch of UDFs and UDAFs
Date Mon, 04 Oct 2010 10:18:35 GMT

    [ https://issues.apache.org/jira/browse/HIVE-1545?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12917546#action_12917546
] 

Terje Marthinussen commented on HIVE-1545:
------------------------------------------

Was just quickly looking at this and noticed that

grep lib com/facebook/hive/udf/*java
com/facebook/hive/udf/UDAFHistogram.java:import com.facebook.hive.udf.lib.Counter;
com/facebook/hive/udf/UDFJaccard.java:import com.facebook.hive.udf.lib.SetOps;

however, there is no com.facebook.hive.udf.lib included.





> Add a bunch of UDFs and UDAFs
> -----------------------------
>
>                 Key: HIVE-1545
>                 URL: https://issues.apache.org/jira/browse/HIVE-1545
>             Project: Hadoop Hive
>          Issue Type: New Feature
>          Components: UDF
>            Reporter: Jonathan Chang
>            Assignee: Jonathan Chang
>            Priority: Minor
>         Attachments: udfs.tar.gz
>
>
> Here some UD(A)Fs which can be incorporated into the Hive distribution:
> UDFArgMax - Find the 0-indexed index of the largest argument. e.g., ARGMAX(4, 5, 3) returns
1.
> UDFBucket - Find the bucket in which the first argument belongs. e.g., BUCKET(x, b_1,
b_2, b_3, ...), will return the smallest i such that x > b_{i} but <= b_{i+1}. Returns
0 if x is smaller than all the buckets.
> UDFFindInArray - Finds the 1-index of the first element in the array given as the second
argument. Returns 0 if not found. Returns NULL if either argument is NULL. E.g., FIND_IN_ARRAY(5,
array(1,2,5)) will return 3. FIND_IN_ARRAY(5, array(1,2,3)) will return 0.
> UDFGreatCircleDist - Finds the great circle distance (in km) between two lat/long coordinates
(in degrees).
> UDFLDA - Performs LDA inference on a vector given fixed topics.
> UDFNumberRows - Number successive rows starting from 1. Counter resets to 1 whenever
any of its parameters changes.
> UDFPmax - Finds the maximum of a set of columns. e.g., PMAX(4, 5, 3) returns 5.
> UDFRegexpExtractAll - Like REGEXP_EXTRACT except that it returns all matches in an array.
> UDFUnescape - Returns the string unescaped (using C/Java style unescaping).
> UDFWhich - Given a boolean array, return the indices which are TRUE.
> UDFJaccard
> UDAFCollect - Takes all the values associated with a row and converts it into a list.
Make sure to have: set hive.map.aggr = false;
> UDAFCollectMap - Like collect except that it takes tuples and generates a map.
> UDAFEntropy - Compute the entropy of a column.
> UDAFPearson (BROKEN!!!) - Computes the pearson correlation between two columns.
> UDAFTop - TOP(KEY, VAL) - returns the KEY associated with the largest value of VAL.
> UDAFTopN (BROKEN!!!) - Like TOP except returns a list of the keys associated with the
N (passed as the third parameter) largest values of VAL.
> UDAFHistogram

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