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From Kapil Malik <kma...@adobe.com>
Subject RE: FlatMapValues
Date Wed, 31 Dec 2014 17:35:27 GMT
Hi Sanjay,

Oh yes .. on flatMapValues, it's defined in PairRDDFunctions, and you need to import org.apache.spark.rdd.SparkContext._
to use them (http://spark.apache.org/docs/latest/api/scala/index.html#org.apache.spark.rdd.PairRDDFunctions
)

@Sean, yes indeed flatMap / flatMapValues both can be used.

Regards,

Kapil 

-----Original Message-----
From: Sean Owen [mailto:sowen@cloudera.com] 
Sent: 31 December 2014 21:16
To: Sanjay Subramanian
Cc: user@spark.apache.org
Subject: Re: FlatMapValues

From the clarification below, the problem is that you are calling flatMapValues, which is
only available on an RDD of key-value tuples.
Your map function returns a tuple in one case but a String in the other, so your RDD is a
bunch of Any, which is not at all what you want. You need to return a tuple in both cases,
which is what Kapil pointed out.

However it's still not quite what you want. Your input is basically [key value1 value2 value3]
so you want to flatMap that to (key,value1)
(key,value2) (key,value3). flatMapValues does not come into play.

On Wed, Dec 31, 2014 at 3:25 PM, Sanjay Subramanian <sanjaysubramanian@yahoo.com> wrote:
> My understanding is as follows
>
> STEP 1 (This would create a pair RDD)
> =======
>
> reacRdd.map(line => line.split(',')).map(fields => {
>   if (fields.length >= 11 && !fields(0).contains("VAERS_ID")) {
>
> (fields(0),(fields(1)+"\t"+fields(3)+"\t"+fields(5)+"\t"+fields(7)+"\t"+fields(9)))
>   }
>   else {
>     ""
>   }
>   })
>
> STEP 2
> =======
> Since previous step created a pair RDD, I thought flatMapValues method 
> will be applicable.
> But the code does not even compile saying that flatMapValues is not 
> applicable to RDD :-(
>
>
> reacRdd.map(line => line.split(',')).map(fields => {
>   if (fields.length >= 11 && !fields(0).contains("VAERS_ID")) {
>
> (fields(0),(fields(1)+"\t"+fields(3)+"\t"+fields(5)+"\t"+fields(7)+"\t"+fields(9)))
>   }
>   else {
>     ""
>   }
>   }).flatMapValues(skus =>
> skus.split('\t')).saveAsTextFile("/data/vaers/msfx/reac/" + outFile)
>
>
> SUMMARY
> =======
> when a dataset looks like the following
>
> 1,red,blue,green
> 2,yellow,violet,pink
>
> I want to output the following and I am asking how do I do that ? 
> Perhaps my code is 100% wrong. Please correct me and educate me :-)
>
> 1,red
> 1,blue
> 1,green
> 2,yellow
> 2,violet
> 2,pink

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