CODEWITHSUNDEEP
scalalist
jeterbord
jeterbord

Reputation: 23

How to pull an element from a sublist?

I have made a list to store some sequences of data, where each sequence contains three elements. How can I extract one of the elements from the sequence?

I have tried parentheses, like alco(0)(1) and get() and they do not work.

val alco = List(("Light Beer", "4%", "23 OZ"), ("Regular Beer", "6%", "23 OZ"))

val temp = alco(0).get(1)

println(temp)

The result shows:

error: value get is not a member of (String, String, String) val temp = alco(0).get(1)

Upvotes: 2

Views: 70

Answers (2)

senjin.hajrulahovic
senjin.hajrulahovic

Reputation: 3181

As @Andriy pointed out:

val alco = List(("Light Beer", "4%", "23 OZ"), ("Regular Beer", "6%", "23 OZ"))

is of type List[Tuple3[String, String, String]] and since Tuple3 does not have a get method you're receiving the error.

scala.Tuple3

To solve the problem just define your list as follows:

val alco = List(List("Light Beer", "4%", "23 OZ"), List("Regular Beer", "6%", "23 OZ"))

This way it will be of type List[List[String]] and your code should work.

Upvotes: 1

Andriy Plokhotnyuk
Andriy Plokhotnyuk

Reputation: 7989

scala> val alco = List(("Light Beer", "4%", "23 OZ"), ("Regular Beer", "6%", "23 OZ"))
alco: List[(String, String, String)] = List((Light Beer,4%,23 OZ), (Regular Beer,6%,23 OZ))

scala> val (_, temp, _) = alco(0)
temp: String = 4%

scala> val temp = alco(0)._2
temp: String = 4%

Beware that accessing to the Scala list by index has O(n) complexity where n is size of the list. So if you want to iterate over them - prefer to use map, collect, foldLeft or foreach calls:

scala> alco.map { case (_, temp, _) => temp }
res0: List[String] = List(4%, 6%)

scala> alco.foreach { x => println(x._2) }
4%
6%

Upvotes: 3

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