CODEWITHSUNDEEP
hiveexplodehiveql
user2726995
user2726995

Reputation: 2062

Hive Explode / Lateral View multiple arrays

I have a hive table with the following schema: 

COOKIE  | PRODUCT_ID | CAT_ID |    QTY    
1234123   [1,2,3]    [r,t,null]  [2,1,null]

How can I normalize the arrays so I get the following result 

COOKIE  | PRODUCT_ID | CAT_ID |    QTY

1234123   [1]          [r]         [2]

1234123   [2]          [t]         [1] 

1234123   [3]          null       null

I have tried the following: 

select concat_ws('|',visid_high,visid_low) as cookie
,pid
,catid 
,qty
from table
lateral view explode(productid) ptable as pid
lateral view explode(catalogId) ptable2 as catid 
lateral view explode(qty) ptable3 as qty

however the result comes out as a Cartesian product.

Upvotes: 22

Views: 61012

Answers (5)

ehacinom
ehacinom

Reputation: 8894

If you are using Spark 2.4 in pyspark, use arrays_zip with posexplode:

df = (df
    .withColumn('zipped', arrays_zip('col1', 'col2'))
    .select('id', posexplode('zipped')))

Upvotes: 1

Lakshman Purihella
Lakshman Purihella

Reputation: 1

I tried to work out on your scenario... please try this code - 

create table info(cookie string,productid int,catid string,qty string);

insert into table info
select cookie,productid[myprod],categoryid[mycat],qty[myqty] from table
lateral view posexplode(productid) pro as myprod,pro
lateral view posexplode(categoryid) cate as mycat,cate
lateral view posexplode(qty) q as myqty,q
where myprod=mycat and mycat=myqty;

Note - In the above statements, if you place - select cookie,myprod,mycat,myqty from table in place of select cookie,productid[myprod],categoryid[mycat],qty[myqty] from table in the output you will get the index of the element in the array of productid, categoryid and qty. Hope this will be helpful.

Upvotes: 0

dataMD
dataMD

Reputation: 159

You can do this by using posexplode, which will provide an integer between 0 and n to indicate the position in the array for each element in the array. Then use this integer - call it pos (for position) to get the matching values in other arrays, using block notation, like this: 

select 
  cookie, 
  n.pos as position, 
  n.prd_id as product_id,
  cat_id[pos] as catalog_id,
  qty[pos] as qty
from table
lateral view posexplode(product_id_arr) n as pos, prd_id;

This avoids the using imported UDF's as well as joining various arrays together (this has much better performance).

Upvotes: 15

Ahmed Abdellatif
Ahmed Abdellatif

Reputation: 369

I found a very good solution to this problem without using any UDF, posexplode is a very good solution :

SELECT COOKIE ,
ePRODUCT_ID,
eCAT_ID,
eQTY
FROM TABLE 
LATERAL VIEW posexplode(PRODUCT_ID) ePRODUCT_IDAS seqp, ePRODUCT_ID
LATERAL VIEW posexplode(CAT_ID) eCAT_ID AS seqc, eCAT_ID
LATERAL VIEW posexplode(QTY) eQTY AS seqq, eDateReported
WHERE seqp = seqc AND seqc = seqq;

Upvotes: 27

Jerome Banks
Jerome Banks

Reputation: 1630

You can use the numeric_range and array_index UDFs from Brickhouse ( http://github.com/klout/brickhouse ) to solve this problem. There is an informative blog posting describing in detail over at http://brickhouseconfessions.wordpress.com/2013/03/07/exploding-multiple-arrays-at-the-same-time-with-numeric_range/

Using those UDFs, the query would be something like 

select cookie,
   array_index( product_id_arr, n ) as product_id,
   array_index( catalog_id_arr, n ) as catalog_id,
   array_index( qty_id_arr, n ) as qty
from table
lateral view numeric_range( size( product_id_arr )) n1 as n;

Upvotes: 16

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