By Alvin Alexander. Last updated: January 17, 2020
This page shows a few examples of methods that can be used to “update” a Scala Vector. Note that these same methods will also work with a Scala Seq, including IndexedSeq.
How to “update” Vector elements
Because Vector is immutable, you can’t update elements in place, but depending on your definition of “update,” there are a variety of methods that let you update a Vector as you assign the result to a new variable:
| Method | Returns |
|---|---|
collect(pf) |
A new collection by applying the partial function pf to all elements of the vector, returning elements for which the function is defined |
distinct |
A new sequence with no duplicate elements |
flatten |
Transforms a list of lists into a single list |
flatMap(f) |
When working with sequences, it works like map followed by flatten |
map(f) |
Return a new sequence by applying the function f to each element in the Vector |
updated(i,v) |
A new vector with the element at index i replaced with the new value v |
union(s) |
A new vector that contains elements from the current vector and the sequence s |
val x = Vector(Some(1), None, Some(3), None)
val y = x.collect{case Some(i) => i} # Vector(1, 3)
val x = Vector(1,2,1,2)
val y = x.distinct # Vector(1, 2)
val y = x.map(_ * 2) # Vector(2, 4, 2, 4)
val y = x.updated(0,100) # Vector(100, 2, 1, 2)
val a = Vector(Seq(1,2), Seq(3,4))
val y = a.flatten # Vector(1, 2, 3, 4)
val fruits = Vector("apple", "pear")
val y = fruits.map(_.toUpperCase) # Vector(APPLE, PEAR)
val y = fruits.flatMap(_.toUpperCase) # Vector(A, P, P, L, E, P, E, A, R)
val y = Vector(2,4).union(Vector(1,3)) # Vector(2, 4, 1, 3)
More information
I created this tutorial to show examples of how to update a Scala Vector or Seq, but for many more examples of how to work with Vector, see my Scala Vector class syntax and method examples tutorial.
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