Tutorial by Examples: accumula

// Java: List<String> list = people.stream().map(Person::getName).collect(Collectors.toList()); // Kotlin: val list = people.map { it.name } // toList() not needed
Have you ever forgotten to add a trap to clean up a temporary file or do other work at exit? Have you ever set one trap which canceled another? This code makes it easy to add things to be done on exit one item at a time, rather than having one large trap statement somewhere in your code, which may...
Accumulators are write-only variables which can be created with SparkContext.accumulator: val accumulator = sc.accumulator(0, name = "My accumulator") // name is optional modified with +=: val someRDD = sc.parallelize(Array(1, 2, 3, 4)) someRDD.foreach(element => accumulator += el...
Define AccumulatorParam import org.apache.spark.AccumulatorParam object StringAccumulator extends AccumulatorParam[String] { def zero(s: String): String = s def addInPlace(s1: String, s2: String)= s1 + s2 } Use: val accumulator = sc.accumulator("")(StringAccumulator) sc.pa...
Define AccumulatorParam: from pyspark import AccumulatorParam class StringAccumulator(AccumulatorParam): def zero(self, s): return s def addInPlace(self, s1, s2): return s1 + s2 accumulator = sc.accumulator("", StringAccumulator()) def add(x): gl...
Python 3.x3.2 accumulate yields a cumulative sum (or product) of numbers. >>> import itertools as it >>> import operator >>> list(it.accumulate([1,2,3,4,5])) [1, 3, 6, 10, 15] >>> list(it.accumulate([1,2,3,4,5], func=operator.mul)) [1, 2, 6, 24, 120] ...
Defined in header <numeric> template<class InputIterator, class T> T accumulate(InputIterator first, InputIterator last, T init); // (1) template<class InputIterator, class T, class BinaryOperation> T accumulate(InputIterator first, InputIterator last, T init, BinaryOperation...
The two mapAccum functions combine the operations of folding and mapping. -- A Traversable structure -- | -- A seed value | ...

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