Spark Scala 26035582 Re-visited -

whilst understand ouctome here, cannot see how highlighted aspects work.
please, enlighten me

def isheavy(inp: string) = inp.split(",")**.map(weights(_))**.sum > 12 

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val input = list("a,b,c,d", "b,c,e", "a,c,d", "e,g")  val splitsize = 10000 // specify number of elements fit in memory.  val numsplits = (input.size / splitsize) + 1 // has > 0. val groups = sc.parallelize(input, numsplits) // specify # of splits.  val weights = array(("a", 3), ("b", 2), ("c", 5), ("d", 1), ("e", 9), ("f", 4), ("g", 6)).tomap  def isheavy(inp: string) = inp.split(",").map(weights(_)).sum > 12 val result = groups.filter(isheavy) 

weights map keyed strings

scala> weights res13: scala.collection.immutable.map[string,int] = map(e -> 9, f -> 4, -> 3, b -> 2, g -> 6, c -> 5, d -> 1) 

inp.split(",") split string, , map function iterates on keys, converting each value of weights map respective key.

the underscore scala shortcut , can written such

inp.split(",").map(x => weights(x)) 

in other words, val input = list("a,b,c,d") becomes list of numbers (3,2,5,1), summed, , filtered out more 12

for example,

scala> input.foreach(x => println(x.split(",").mkstring)) abcd bce acd eg  scala> input.foreach(x => println(x.split(",").map(weights(_)).mkstring(","))) 3,2,5,1 2,5,9 3,5,1 9,6  scala> input.foreach(x => println(x.split(",").map(weights(_)).sum)) 11 16 9 15  scala> input.foreach(x => {      |     val sum = x.split(",").map(weights(_)).sum      |     if (sum > 12) println(sum)      | }) 16 15