Sort array in Scala partially

Question

How can I sort a region in an array in Scala?

I have an array, say var DivA = new Array[Int](100005).

I filled the elements in DivA up to some position which is less than 100005. For example my array looks like Diva = {1,2,10,5,15,20}.

In C++ we have sort(DivA, DivA + N), but how can we sort arrays in Scala up to a certain index?

I tried Sorting.quickSort(DivA), but I don't know how to define the index up to which I want to sort the array, so that the statement above sorts the array, and the array looks like DivA={0,0,0,0,0}?

      var Diva=new Array[Int](10000);
      for(j<-15 to 0 by -1){
           DivA(posA)=j;
           posA=posA+1;
      }
      Sorting.quickSort(DivA);

      for(j<-0 to posA-1)
        {
          print(DivA(j));
          print(" ");
        }

Beryllium · Accepted Answer · 2014-03-23 14:31:07Z

2

If you want to sort a region in an array, you can use the sort method in java.util.Arrays:

java.util.Arrays.sort(DivA, 0, 15)

this method offers fromIndex and toIndex. Note that this method sorts in place. That's probably OK in your case, as the style you apply seems to be "imperative".

If performance matters, arrays will probably be faster than other collections. Other reasons for using arrays might be memory consumption or interoperability.

Otherwise you can probably design your data structures/algorithm in a different (more "functional") way by using idiomatic Scala collections.

edited Mar 23, 2014 at 14:31

answered Mar 23, 2014 at 14:19

Beryllium

13k11 gold badges59 silver badges88 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Patryk Ćwiek · Accepted Answer · 2014-03-23 13:24:03Z

1

You can use sorted or sortBy, depending on your needs. In case of simple Array[Int], sorted should be enough:

val arr = Array.iterate(15, 15)(_ - 1)
arr: Array[Int] = Array(15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1)

val sortedArray = arr.sorted
sortedArray: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)

You can provide your own Ordering typeclass if you want some other kind of order.

You can find it in the documentation.

Although, as was noted in other answer, you should prefer immutable Vector unless you have good reason to switch to Array.

answered Mar 23, 2014 at 13:24

Patryk Ćwiek

14.3k3 gold badges58 silver badges78 bronze badges

Comments

user537862 · Accepted Answer · 2014-03-23 13:24:11Z

1

sorted() method is common for all collections, and Arrays in Scala are implicitly converted to a collection. So you can call sorted on Array[Int], eg:

scala> val p = (10 to 1 by -1).toArray
p: Array[Int] = Array(10, 9, 8, 7, 6, 5, 4, 3, 2, 1)

scala> p.sorted
res5: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

answered Mar 23, 2014 at 13:24

user537862

4912 silver badges6 bronze badges

Comments

mister11 · Accepted Answer · 2014-03-23 12:47:49Z

0

First, if you are programming in Scala, you should think about Vector or List because those are immutable which is prefferd way of programming in Scala...

And for Vector and List there is sorted() function which sorts an array

answered Mar 23, 2014 at 12:47

mister11

822 silver badges9 bronze badges

1 Comment

chandan111 Over a year ago

i read about list and vector but is there no any way to sort array of integer ?

Collectives™ on Stack Overflow

Sort array in Scala partially

4 Answers 4

Comments

Comments

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related