Spark has a more limited API than Java and Scala, but supports most of the core functionalities.
The hallmarks of a MapReduce system are the two commands:
reduce. You've seen the
map function used in the past chapters. The
map function works by taking in a function that works on each individual element in the input RDD and produces a new output element. For example, to produce a new RDD where you have added one to every number, you would use
rdd.map(lambda x: x+1). It's important to understand that the
map function and the other Spark functions do not transform the existing elements, rather they return a new RDD with the new elements. The
reduce function takes a function that operates on pairs to combine ...