Getting elements from DataStream

[subash basnet]

Hello all,

Getting certain number of elements from DataSet is possible as below:
*DataSet<Centroid> centroids = newDataSet.map(new
TupleCentroidConverter()).first(3);*

How could I get elements as above in DataStream
*DataStream<Centroid> centroids = newDataStream.map(new
TupleCentroidConverter()).???*


Best Regards,
Subash Basnet