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https://github.com/jozic/scalax-collection
A small library of extension methods for standard scala collections library
https://github.com/jozic/scalax-collection
extension scala scalax-collection
Last synced: about 20 hours ago
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A small library of extension methods for standard scala collections library
- Host: GitHub
- URL: https://github.com/jozic/scalax-collection
- Owner: jozic
- License: bsd-3-clause
- Created: 2014-07-17T04:08:31.000Z (over 10 years ago)
- Default Branch: main
- Last Pushed: 2022-12-31T02:24:32.000Z (almost 2 years ago)
- Last Synced: 2023-07-02T06:03:40.499Z (over 1 year ago)
- Topics: extension, scala, scalax-collection
- Language: Scala
- Homepage:
- Size: 112 KB
- Stars: 6
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
scalax-collection [](https://github.com/jozic/scalax-collection/actions/workflows/build.yml/badge.svg) [](https://coveralls.io/r/jozic/scalax-collection)
=================
A small library of extension methods for standard scala collections library.
Published to maven central.
| 2.10 | 2.11 | 2.12 | 2.13 | 3 |
|------|------|------|------| - |
|[](https://maven-badges.herokuapp.com/maven-central/com.daodecode/scalax-collection_2.10) | [](https://maven-badges.herokuapp.com/maven-central/com.daodecode/scalax-collection_2.11) | [](https://maven-badges.herokuapp.com/maven-central/com.daodecode/scalax-collection_2.12) | [](https://maven-badges.herokuapp.com/maven-central/com.daodecode/scalax-collection_2.13) | [](https://maven-badges.herokuapp.com/maven-central/com.daodecode/scalax-collection_3) |
## Collection Examples
An import needed for examples to work:
```scala
import com.daodecode.scalax.collection.extensions._
```
### distinctBy
preserving first duplicate
```scala
val xs = List(1 -> "one", 1 -> "ten", 2 -> "two", 2 -> "twenty").distinctBy(_._1)
// xs: List[(Int, String)] = List((1, "one"), (2, "two"))
```
*NOTE: Since Scala 2.13 this method is available in standard library*
### distinctByUsing
or preserving any duplicate you want
```scala
val xs = List(1 -> "one", 1 -> "ten", 2 -> "two", 2 -> "twenty").distinctByUsing(_._1, takeFirst = _._2.length > _._2.length)
// xs: List[(Int, String)] = List((1, "ten"), (2, "twenty"))
```
*NOTE: Before 0.3.0 this method was named `distinctBy`*
### foldLeftWhile/foldRightWhile
```scala
val xs = Iterable(List(1,2,3), List(4,5), List(6,7,8,9)).foldLeftWhile(List.empty[Int])(_.size < 4){ case (acc, l) => acc ++ l }
// xs: List[Int] = List(1, 2, 3, 4, 5)
```
### toCompleteMap
*since Scala 2.13 can be seen as equivalent to `groupMap(_._1)(_._2)`*
```scala
val cm = List(1 -> "1", 2 -> "2", 1 -> "11").toCompleteMap
// cm: Map[Int, List[String]] = Map(1 -> List("1", "11"), 2 -> List("2"))
```
### mapToMap
*can be seen as more efficient replacement for `map().toMap` combination*
```scala
val m = List("1" -> "one", "2" -> "two").mapToMap { case (i, s) => i.toInt -> s }
// m: Map[Int, String] = Map(1 -> "one", 2 -> "two")
```
### toMapWithKey
*since Scala 2.13 can be seen as equivalent to `groupMapReduce(f)(identity)((b,_) => b)`*
```scala
val m = List("1", "2", "1").toMapWithKey(_.toInt)
// m: Map[Int, String] = Map(1 -> "1", 2 -> "2")
```
### toMapWithValue
*since Scala 2.13 can be seen as equivalent to `groupMapReduce(identity)(f)((b,_) => b)`*
```scala
val m = List("1", "2", "1").toMapWithValue(_.toInt)
// m: Map[String, Int] = Map("1" -> 1, "2" -> 2)
```
### withFrequency
*since Scala 2.13 can be seen as equivalent to `groupMapReduce(identity)(_ => 1)(_ + _)`*
```scala
val fm = List("a", "b", "c", "a", "b", "d").withFrequency
// fm: Map[String, Int] = Map("a" -> 2, "b" -> 2, "c" -> 1, "d" -> 1)
```
### withFrequencyBy
*since Scala 2.13 can be seen as equivalent to `groupMapReduce(f)(_ => 1)(_ + _)`*
```scala
val fm = List("ab", "bc", "cd", "ab", "bc", "de").withFrequencyBy(_.head)
// fm: Map[Char, Int] = Map('a' -> 2, 'b' -> 2, 'c' -> 1, 'd' -> 1)
```
### mergedWith
Merges two maps using provided function to merge values for duplicate keys
```scala
val merged = Map("1" -> 1, "2" -> 2).mergedWith(Map("1" -> 1, "2" -> 2))(_ + _)
// merged: Map[String, Int] = Map("1" -> 2, "2" -> 4)
```
### minOption/minOptionBy
Finds the smallest element wrapped in `Option` or `None` if iterable is empty
```scala
val m1 = List.empty[Int].minOption
// m1: Option[Int] = None
val m2 = List(1,2,1).minOptionBy(_ * -1)
// m2: Option[Int] = Some(value = 2)
```
*NOTE: Since Scala 2.13 this is available in standard library*
### maxOption/maxOptionBy
Finds the largest element wrapped in `Option` or `None` if iterable is empty
```scala
val m1 = List.empty[Int].maxOption
// m1: Option[Int] = None
val m2 = List(1,2,1).maxOptionBy(_ * -1)
// m2: Option[Int] = Some(value = 1)
```
*NOTE: Since Scala 2.13 this is available in standard library*
### unzip4/unzip5/unzip6
Similar to `unzip` and `unzip3` from standard library, but for tuples of higher arity (up to 6)
```scala
val (ints, strings, chars, doubles) =
Iterable(
(1, "one", '1', 1d),
(2, "two", '2', 2d),
(3, "three", '3', 3d),
(4, "four", '4', 4d)
).unzip4
// ints: Iterable[Int] = List(1, 2, 3, 4)
// strings: Iterable[String] = List("one", "two", "three", "four")
// chars: Iterable[Char] = List('1', '2', '3', '4')
// doubles: Iterable[Double] = List(1.0, 2.0, 3.0, 4.0)
```
## Strings Examples
An import needed for examples to work:
```scala
import com.daodecode.scalax._
```
### NonEmptyString
```scala
NonEmptyString(null)
// res0: Option[String] = None
NonEmptyString("")
// res1: Option[String] = None
NonEmptyString(" a ")
// res2: Option[String] = Some(value = " a ")
(null: String) match {
case NonEmptyString(_) => "boo"
case _ => "works!"
}
// res3: String = "works!"
"" match {
case NonEmptyString(_) => "boo"
case _ => "works!"
}
// res4: String = "works!"
"works!" match {
case NonEmptyString(s) => s
case _ => "boo"
}
// res5: String = "works!"
```
### NonBlankString
```scala
NonBlankString(null)
// res6: Option[String] = None
NonBlankString("")
// res7: Option[String] = None
NonBlankString(" \n \r \t ")
// res8: Option[String] = None
NonBlankString(" a ")
// res9: Option[String] = Some(value = " a ")
(null: String) match {
case NonBlankString(_) => "boo"
case _ => "works!"
}
// res10: String = "works!"
"" match {
case NonBlankString(_) => "boo"
case _ => "works!"
}
// res11: String = "works!"
" \t " match {
case NonBlankString(_) => "boo"
case _ => "works!"
}
// res12: String = "works!"
"works!" match {
case NonBlankString(s) => s
case _ => "boo"
}
// res13: String = "works!"
```
### NonBlankTrimmedString
```scala
NonBlankTrimmedString(null)
// res14: Option[String] = None
NonBlankTrimmedString("")
// res15: Option[String] = None
NonBlankTrimmedString(" \n \r \t ")
// res16: Option[String] = None
NonBlankTrimmedString(" a ")
// res17: Option[String] = Some(value = "a")
(null: String) match {
case NonBlankTrimmedString(_) => "boo"
case _ => "works!"
}
// res18: String = "works!"
"" match {
case NonBlankTrimmedString(_) => "boo"
case _ => "works!"
}
// res19: String = "works!"
" \t " match {
case NonBlankTrimmedString(_) => "boo"
case _ => "works!"
}
// res20: String = "works!"
" works!\n " match {
case NonBlankTrimmedString(s) => s
case _ => "boo"
}
// res21: String = "works!"
```
## Latest stable release
### sbt
```scala
libraryDependencies += "com.daodecode" %% "scalax-collection" % "0.3.2"
```
### maven
set `` property to scala version you need, like
```xml
2.13
```
and then in `dependencies` add
```xml
com.daodecode
scalax-collection_${scala.binary.version}
0.3.2
```