Thanks TD, this is what I was looking for. rdd.context.makeRDD worked.
Laeeq
On Friday, March 13, 2015 11:08 PM, Tathagata Das <[email protected]>
wrote:
Is the number of top K elements you want to keep small? That is, is K small?
In which case, you can1. either do it in the driver on the array
DStream.foreachRDD ( rdd => { val topK = rdd.top(K) ; // use top K })
2. Or, you can use the topK to create another RDD using sc.makeRDD
DStream.transform ( rdd => { val topK = rdd.top(K) ;
rdd.context.makeRDD(topK, numPartitions)})
TD
On Fri, Mar 13, 2015 at 5:58 AM, Laeeq Ahmed <[email protected]>
wrote:
Hi,
Earlier my code was like follwing but slow due to repartition. I want top K of
each window in a stream.
val counts = keyAndValues.map(x =>
math.round(x._3.toDouble)).countByValueAndWindow(Seconds(4), Seconds(4))val
topCounts = counts.repartition(1).map(_.swap).transform(rdd =>
rdd.sortByKey(false)).map(_.swap).mapPartitions(rdd => rdd.take(10))
so I thought to use dstream.transform(rdd=>rdd.top()) but this return Array
rather than rdd. I have to perform further steps on topCounts dstream.
[ERROR] found : Array[(Long, Long)][ERROR] required:
org.apache.spark.rdd.RDD[?][ERROR] val topCounts = counts.transform(rdd =>
rdd.top(10))
Regards,Laeeq
On Friday, March 13, 2015 1:47 PM, Sean Owen <[email protected]> wrote:
Hm, aren't you able to use the SparkContext here? DStream operations
happen on the driver. So you can parallelize() the result?
take() won't work as it's not the same as top()
On Fri, Mar 13, 2015 at 11:23 AM, Akhil Das <[email protected]> wrote:
> Like this?
>
> dtream.repartition(1).mapPartitions(it => it.take(5))
>
>
>
> Thanks
> Best Regards
>
> On Fri, Mar 13, 2015 at 4:11 PM, Laeeq Ahmed <[email protected]>
> wrote:
>>
>> Hi,
>>
>> I normally use dstream.transform whenever I need to use methods which are
>> available in RDD API but not in streaming API. e.g. dstream.transform(x =>
>> x.sortByKey(true))
>>
>> But there are other RDD methods which return types other than RDD. e.g.
>> dstream.transform(x => x.top(5)) top here returns Array.
>>
>> In the second scenario, how can i return RDD rather than array, so that i
>> can perform further steps on dstream.
>>
>> Regards,
>> Laeeq
>
>
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