representation of values (x,y) vs x._1,y._1

Question

I am new to spark using scala and very much confused by the notations (x,y) in some scenarios and x._1, y._1. Especially when they are used one over the other in spark transformations

could someone explain is there a specific rule of thumb for when to use each of these syntaxes

Use `(x,y)` with proper naming as it's easier to understand. — Nikita, Jul 21 '16 at 17:48

score 3 · Answer 1 · answered Jul 21 '16 at 18:44

Basically there are 2 ways to access a tuple parameter in anonymous function. They're functionally equivalent, use whatever method you prefer.

Through the attributes _1, _2,...

Through pattern matching into variable with meaningful name

val tuples = Array((1, 2), (2, 3), (3, 4))

// Attributes
tuples.foreach { t => 
  println(s"${t._1} ${t._2}")
}

// Pattern matching
tuples.foreach { t =>
  t match {
    case (first, second) =>
      println(s"$first $second")
  }
}

// Pattern matching can also written as
tuples.foreach { case (first, second) =>
    println(s"$first $second")
}

Jesper · Answer 2 · 2022-07-27T06:23:53.970

The notation (x, y) is a tuple of 2 elements, x and y. There are different ways to get access to the individual values in a tuple. You can use the ._1, ._2 notation to get at the elements:

val tup = (3, "Hello")    // A tuple with two elements

val number = tup._1       // Gets the first element (3) from the tuple
val text = tup._2         // Gets the second element ("Hello") from the tuple

You can also use pattern matching. One way to extract the two values is like this:

val (number, text) = tup

Unlike a collection (for example, a List) a tuple has a fixed number of values (it's not always exactly two values) and the values can have different types (such as an Int and a String in the example above).

There are many tutorials about Scala tuples, for example: Scala tuple examples and syntax.

representation of values (x,y) vs x._1,y._1

2 Answers2