CODEWITHSUNDEEP
scalaapache-sparkanonymous-function
vijay
vijay

Reputation: 1233

Anonymous function inside a method in Scala

I was looking at one of the sample codes (given below). I notice what looks like an anonymous function (line below //what is this comment in the snippet) defined inside this method. What exactly is this and how does this get invoked? 

 def initHasher(requestFilePath: String) = {
      import spark.implicits._
      val hashes = spark.read.option("delimiter", ",").option("header", "true").csv(requestFilePath)
        .select($"Hash", $"Count").rdd
        .map(r => (r.getString(0), r.getString(1))).collectAsMap()
      val broadcastedHashes = spark.sparkContext.broadcast(hashes)

// What is this?
      (str: String) => {
        if (str != null && str.length > 0) {
          val hash = sha256hash(str)
          broadcastedHashes.value.get(hash) match {
            case None => hash
            case Some(count) => sha256hash(str + ":" + count)
          }
        }
        else
          null
      }
    }

Upvotes: 0

Views: 277

Answers (1)

Ayush
Ayush

Reputation: 42440

initHasher initializes a hasher and returns it as a function (the anonymous function you are seeing). It would be used like this:

// initialize your hasher here
val hasher = initHasher(requestFilePath)

// now you can use the hasher
val hash = hasher("my string")

Upvotes: 4

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