A small library of extension methods for standard scala collections library. Published to maven central.
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An import needed for examples to work:
import com.daodecode.scalax.collection.extensions._preserving first duplicate
val xs = List(1 -> "one", 1 -> "ten", 2 -> "two", 2 -> "twenty").distinctBy(_._1)NOTE: Since Scala 2.13 this method is available in standard library
or preserving any duplicate you want
val xs = List(1 -> "one", 1 -> "ten", 2 -> "two", 2 -> "twenty").distinctByUsing(_._1, takeFirst = _._2.length > _._2.length)NOTE: Before 0.3.0 this method was named distinctBy
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 }since Scala 2.13 can be seen as equivalent to groupMap(_._1)(_._2)
val cm = List(1 -> "1", 2 -> "2", 1 -> "11").toCompleteMapcan be seen as more efficient replacement for map().toMap combination
val m = List("1" -> "one", "2" -> "two").mapToMap { case (i, s) => i.toInt -> s }since Scala 2.13 can be seen as equivalent to groupMapReduce(f)(identity)((b,_) => b)
val m = List("1", "2", "1").toMapWithKey(_.toInt)since Scala 2.13 can be seen as equivalent to groupMapReduce(identity)(f)((b,_) => b)
val m = List("1", "2", "1").toMapWithValue(_.toInt)since Scala 2.13 can be seen as equivalent to groupMapReduce(identity)(_ => 1)(_ + _)
val fm = List("a", "b", "c", "a", "b", "d").withFrequencysince Scala 2.13 can be seen as equivalent to groupMapReduce(f)(_ => 1)(_ + _)
val fm = List("ab", "bc", "cd", "ab", "bc", "de").withFrequencyBy(_.head)Merges two maps using provided function to merge values for duplicate keys
val merged = Map("1" -> 1, "2" -> 2).mergedWith(Map("1" -> 1, "2" -> 2))(_ + _)Finds the smallest element wrapped in Option or None if iterable is empty
val m1 = List.empty[Int].minOption
val m2 = List(1,2,1).minOptionBy(_ * -1)NOTE: Since Scala 2.13 this is available in standard library
Finds the largest element wrapped in Option or None if iterable is empty
val m1 = List.empty[Int].maxOption
val m2 = List(1,2,1).maxOptionBy(_ * -1)NOTE: Since Scala 2.13 this is available in standard library
Similar to unzip and unzip3 from standard library, but for tuples of higher arity (up to 6)
val (ints, strings, chars, doubles) =
Iterable(
(1, "one", '1', 1d),
(2, "two", '2', 2d),
(3, "three", '3', 3d),
(4, "four", '4', 4d)
).unzip4An import needed for examples to work:
import com.daodecode.scalax._NonEmptyString(null)
NonEmptyString("")
NonEmptyString(" a ")
(null: String) match {
case NonEmptyString(_) => "boo"
case _ => "works!"
}
"" match {
case NonEmptyString(_) => "boo"
case _ => "works!"
}
"works!" match {
case NonEmptyString(s) => s
case _ => "boo"
}NonBlankString(null)
NonBlankString("")
NonBlankString(" \n \r \t ")
NonBlankString(" a ")
(null: String) match {
case NonBlankString(_) => "boo"
case _ => "works!"
}
"" match {
case NonBlankString(_) => "boo"
case _ => "works!"
}
" \t " match {
case NonBlankString(_) => "boo"
case _ => "works!"
}
"works!" match {
case NonBlankString(s) => s
case _ => "boo"
}NonBlankTrimmedString(null)
NonBlankTrimmedString("")
NonBlankTrimmedString(" \n \r \t ")
NonBlankTrimmedString(" a ")
(null: String) match {
case NonBlankTrimmedString(_) => "boo"
case _ => "works!"
}
"" match {
case NonBlankTrimmedString(_) => "boo"
case _ => "works!"
}
" \t " match {
case NonBlankTrimmedString(_) => "boo"
case _ => "works!"
}
" works!\n " match {
case NonBlankTrimmedString(s) => s
case _ => "boo"
}libraryDependencies += "com.daodecode" %% "scalax-collection" % "0.3.2"set <scala.binary.version> property to scala version you need, like
<properties>
<scala.binary.version>2.13</scala.binary.version>
</properties>
and then in dependencies add
<dependency>
<groupId>com.daodecode</groupId>
<artifactId>scalax-collection_${scala.binary.version}</artifactId>
<version>0.3.2</version>
</dependency>