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From Michael Armbrust <mich...@databricks.com>
Subject Re: Remapping columns from a schemaRDD
Date Tue, 25 Nov 2014 18:44:38 GMT
Maps should just be scala maps, structs are rows inside of rows.  If you
wan to return a struct from a UDF you can do that with a case class.

On Tue, Nov 25, 2014 at 10:25 AM, Daniel Haviv <danielrulez@gmail.com>
wrote:

> Thank you.
>
> How can I address more complex columns like maps and structs?
>
> Thanks again!
> Daniel
>
> On 25 בנוב׳ 2014, at 19:43, Michael Armbrust <michael@databricks.com>
> wrote:
>
> Probably the easiest/closest way to do this would be with a UDF, something
> like:
>
> registerFunction("makeString", (s: Seq[String]) => s.mkString(","))
> sql("SELECT *, makeString(c8) AS newC8 FROM jRequests")
>
> Although this does not modify a column, but instead appends a new column.
>
> Another more complicated way to do something like this would be by using the
> applySchema function
> <http://spark.apache.org/docs/latest/sql-programming-guide.html#programmatically-specifying-the-schema>
> .
>
> I'll note that, as part of the ML pipeline work, we have been considering
> adding something like:
>
> def modifyColumn(columnName, function)
>
> Any comments anyone has on this interface would be appreciated!
>
> Michael
>
> On Tue, Nov 25, 2014 at 7:02 AM, Daniel Haviv <danielrulez@gmail.com>
> wrote:
>
>> Hi,
>> I'm selecting columns from a json file, transform some of them and would
>> like to store the result as a parquet file but I'm failing.
>>
>> This is what I'm doing:
>>
>> val jsonFiles=sqlContext.jsonFile("/requests.loading")
>> jsonFiles.registerTempTable("jRequests")
>>
>> val clean_jRequests=sqlContext.sql("select c1, c2, c3 ... c55 from
>> jRequests")
>>
>> and then I run a map:
>>  val
>> jRequests_flat=clean_jRequests.map(line=>{((line(1),line(2),line(3),line(4),line(5),line(6),line(7),
>> *line(8).asInstanceOf[Iterable[String]].mkString(",")*,line(9) ,line(10)
>> ,line(11) ,line(12) ,line(13) ,line(14) ,line(15) ,line(16) ,line(17)
>> ,line(18) ,line(19) ,line(20) ,line(21) ,line(22) ,line(23) ,line(24)
>> ,line(25) ,line(26) ,line(27) ,line(28) ,line(29) ,line(30) ,line(31)
>> ,line(32) ,line(33) ,line(34) ,line(35) ,line(36) ,line(37) ,line(38)
>> ,line(39) ,line(40) ,line(41) ,line(42) ,line(43) ,line(44) ,line(45)
>> ,line(46) ,line(47) ,line(48) ,line(49) ,line(50)))})
>>
>>
>>
>> 1. Is there a smarter way to achieve that (only modify a certain column
>> without relating to the others, but keeping all of them)?
>> 2. The last statement fails because the tuple has too much members:
>> <console>:19: error: object Tuple50 is not a member of package scala
>>
>>
>> Thanks for your help,
>> Daniel
>>
>>
>

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