i see it works well，thank you!!!
But in follow situation how to do
var a = sc.textFile("/sparktest/1/").map((_,"a"))
var b = sc.textFile("/sparktest/2/").map((_,"b"))
How to get (3,"a") and (4,"a")????
在 Aug 28, 2014，19:54，"Matthew Farrellee" <m...@redhat.com> 写道：
> On 08/28/2014 07:20 AM, marylucy wrote:
>> fileA=1 2 3 4 one number a line,save in /sparktest/1/
>> fileB=3 4 5 6 one number a line,save in /sparktest/2/
>> I want to get 3 and 4
>>
>> var a = sc.textFile("/sparktest/1/").map((_,1))
>> var b = sc.textFile("/sparktest/2/").map((_,1))
>>
>> a.filter(param=>{b.lookup(param._1).length>0}).map(_._1).foreach(println)
>>
>> Error throw
>> Scala.MatchError:Null
>> PairRDDFunctions.lookup...
>
> the issue is nesting of the b rdd inside a transformation of the a rdd
>
> consider using intersection, it's more idiomatic
>
> a.intersection(b).foreach(println)
>
> but not that intersection will remove duplicates
>
> best,
>
>
> matt
>
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