How come transformation methods of Spark like map, reduce, filter also in Scala (without Spark)?

[Monica Shiralkar]

In Spark, there are transformation methods like map, reduce, filter. These methods are specific to Spark and are  called Spark transformations. Howcome these methods are present in Scala programming language (without Spark).

Thanks

[Stephan van Hulst]

Mapping, filtering and reducing are some of the most essential operations in any functional language. Scala needs them regardless of whether you use Spark or not.

A better question is, why does Spark for Scala feel that it needs separate versions of these functions?

[Monica Shiralkar]

I think the answer to the question you said as the better question  to ask is that since Spark requires these methods to do the work they are intended to on a cluster of machines  so they require a different version of these methods. That is what I think. I may be wrong.

[Gabriel Claramunt]

Spark got inspired for  it's API from Scala's collection API that has those methods (filter, map, flatMap, reduce, etc). When invoked in a Scala collection, they run locally, returning a new collection, when using Spark, the methods will be invoked on the RDD API, and will return a transformed RDD that will run in the Spark cluster.