Scala 3

Learn Install Playground Find A Library Community Blog

Docs API

Generated with

Scala 3/scala/scala.math/Ordering

Ordering

scala.math.Ordering

See theOrdering companion object

traitOrdering[T] extendsComparator[T],PartialOrdering[T],Serializable

Ordering is a trait whose instances each represent a strategy for sorting instances of a type.

Ordering's companion object defines many implicit objects to deal with subtypes ofAnyVal (e.g.Int,Double),String, and others.

To sort instances by one or more member variables, you can take advantage of these built-in orderings usingOrdering.by andOrdering.on:

import scala.util.Sortingval pairs = Array(("a", 5, 2), ("c", 3, 1), ("b", 1, 3))// sort by 2nd elementSorting.quickSort(pairs)(Ordering.by[(String, Int, Int), Int](_._2))// sort by the 3rd element, then 1stSorting.quickSort(pairs)(Ordering[(Int, String)].on(x => (x._3, x._1)))

AnOrdering[T] is implemented by specifying thecompare method,compare(a: T, b: T): Int, which decides how to order two instancesa andb. Instances ofOrdering[T] can be used by things likescala.util.Sorting to sort collections likeArray[T].

For example:

import scala.util.Sortingcase class Person(name:String, age:Int)val people = Array(Person("bob", 30), Person("ann", 32), Person("carl", 19))// sort by ageobject AgeOrdering extends Ordering[Person] { def compare(a:Person, b:Person) = a.age.compare(b.age)}Sorting.quickSort(people)(AgeOrdering)

This trait andscala.math.Ordered both provide this same functionality, but in different ways. A typeT can be given a single way to order itself by extendingOrdered. UsingOrdering, this same type may be sorted in many other ways.Ordered andOrdering both provide implicits allowing them to be used interchangeably.

You canimport scala.math.Ordering.Implicits._ to gain access to other implicit orderings.

Attributes

See also: scala.math.Ordered,scala.util.Sorting,scala.math.Ordering.Implicits
Companion: object
Source: Ordering.scala
Graph
Supertypes: traitPartialOrdering[T]
traitEquiv[T]
traitSerializable
traitComparator[T]
classObject
traitMatchable
classAny
Show all
Known subtypes: objectDeadlineIsOrdered
objectDurationIsOrdered
objectFiniteDurationIsOrdered
objectEnumeration.this.ValueOrdering
traitNumeric[T]
traitFractional[T]
traitBigDecimalIsFractional
objectBigDecimalIsFractional
traitDoubleIsFractional
objectDoubleIsFractional
traitFloatIsFractional
objectFloatIsFractional
traitIntegral[T]
traitBigDecimalAsIfIntegral
objectBigDecimalAsIfIntegral
traitBigIntIsIntegral
objectBigIntIsIntegral
traitByteIsIntegral
objectByteIsIntegral
traitCharIsIntegral
objectCharIsIntegral
traitIntIsIntegral
objectIntIsIntegral
traitLongIsIntegral
objectLongIsIntegral
traitShortIsIntegral
objectShortIsIntegral
traitBigDecimalIsConflicted
traitBigDecimalOrdering
objectBigDecimal
traitBigIntOrdering
objectBigInt
traitBooleanOrdering
objectBoolean
traitByteOrdering
objectByte
traitCachedReverse[T]
objectInt
traitCharOrdering
objectChar
traitIeeeOrdering
objectIeeeOrdering
traitTotalOrdering
objectDeprecatedDoubleOrdering
objectTotalOrdering
traitIeeeOrdering
objectIeeeOrdering
traitTotalOrdering
objectDeprecatedFloatOrdering
objectTotalOrdering
traitIntOrdering
traitLongOrdering
objectLong
traitOptionOrdering[T]
traitShortOrdering
objectShort
traitStringOrdering
objectString
traitSymbolOrdering
objectSymbol
traitUnitOrdering
objectUnit
Show all
Self type: Ordering[T]

Members list

Type members

Classlikes

classOrderingOps(lhs:Ordering.this.T)

Implicitly added byIterable

This inner class defines comparison operators available forT.

It can't extendAnyVal because it is not a top-level class or a member of a statically accessible object.

Attributes

Source: Ordering.scala
Supertypes: classObject
traitMatchable
classAny

classOrderingOps(lhs:Ordering.this.T)

Implicitly added byOption

This inner class defines comparison operators available forT.

It can't extendAnyVal because it is not a top-level class or a member of a statically accessible object.

Attributes

Source: Ordering.scala
Supertypes: classObject
traitMatchable
classAny

classOrderingOps(lhs:Ordering.this.T)

This inner class defines comparison operators available forT.

It can't extendAnyVal because it is not a top-level class or a member of a statically accessible object.

Attributes

Source: Ordering.scala
Supertypes: classObject
traitMatchable
classAny

Value members

Abstract methods

defcompare(x:T,y:T):Int

Implicitly added byIterable

Returns an integer whose sign communicates how x compares to y.

The result sign has the following meaning:

- negative if x < y - positive if x > y - zero otherwise (if x == y)

Attributes

Source: Ordering.scala

defcompare(x:T,y:T):Int

Implicitly added byOption

Returns an integer whose sign communicates how x compares to y.

The result sign has the following meaning:

- negative if x < y - positive if x > y - zero otherwise (if x == y)

Attributes

Source: Ordering.scala

defcompare(x:T,y:T):Int

Returns an integer whose sign communicates how x compares to y.

The result sign has the following meaning:

- negative if x < y - positive if x > y - zero otherwise (if x == y)

Attributes

Source: Ordering.scala

Concrete methods

overridedefequiv(x:T,y:T):Boolean

Return true ifx ==y in the ordering.

Attributes

Definition Classes: PartialOrdering ->Equiv
Source: Ordering.scala

overridedefgt(x:T,y:T):Boolean

Return true ifx >y in the ordering.

Attributes

Definition Classes: PartialOrdering
Source: Ordering.scala

overridedefgteq(x:T,y:T):Boolean

Return true ifx >=y in the ordering.

Attributes

Definition Classes: PartialOrdering
Source: Ordering.scala

defisReverseOf(other:Ordering[_]):Boolean

Implicitly added byIterable

Returns whether or not the other ordering is the opposite ordering of this one.

Equivalent toother == this.reverse.

Implementations should only override this method if they are overridingreverse as well.

Attributes

Source: Ordering.scala

defisReverseOf(other:Ordering[_]):Boolean

Implicitly added byOption

Returns whether or not the other ordering is the opposite ordering of this one.

Equivalent toother == this.reverse.

Implementations should only override this method if they are overridingreverse as well.

Attributes

Source: Ordering.scala

defisReverseOf(other:Ordering[_]):Boolean

Returns whether or not the other ordering is the opposite ordering of this one.

Equivalent toother == this.reverse.

Implementations should only override this method if they are overridingreverse as well.

Attributes

Source: Ordering.scala

overridedeflt(x:T,y:T):Boolean

Return true ifx <y in the ordering.

Attributes

Definition Classes: PartialOrdering
Source: Ordering.scala

overridedeflteq(x:T,y:T):Boolean

Return true ifx <=y in the ordering.

Attributes

Definition Classes: PartialOrdering
Source: Ordering.scala

defmax[U <:T](x:U,y:U):U

Implicitly added byIterable

Returnx ifx >=y, otherwisey.

Attributes

Source: Ordering.scala

defmax[U <:T](x:U,y:U):U

Implicitly added byOption

Returnx ifx >=y, otherwisey.

Attributes

Source: Ordering.scala

defmax[U <:T](x:U,y:U):U

Returnx ifx >=y, otherwisey.

Attributes

Source: Ordering.scala

defmin[U <:T](x:U,y:U):U

Implicitly added byIterable

Returnx ifx <=y, otherwisey.

Attributes

Source: Ordering.scala

defmin[U <:T](x:U,y:U):U

Implicitly added byOption

Returnx ifx <=y, otherwisey.

Attributes

Source: Ordering.scala

defmin[U <:T](x:U,y:U):U

Returnx ifx <=y, otherwisey.

Attributes

Source: Ordering.scala

defon[U](f:U=>T):Ordering[U]

Implicitly added byIterable

Given f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:

def compare(x:U, y:U) = Ordering[T].compare(f(x), f(y))

Attributes

Source: Ordering.scala

defon[U](f:U=>T):Ordering[U]

Implicitly added byOption

Given f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:

def compare(x:U, y:U) = Ordering[T].compare(f(x), f(y))

Attributes

Source: Ordering.scala

defon[U](f:U=>T):Ordering[U]

Given f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:

def compare(x:U, y:U) = Ordering[T].compare(f(x), f(y))

Attributes

Source: Ordering.scala

deforElse(other:Ordering[T]):Ordering[T]

Implicitly added byIterable

Creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result ofothers compare function.

Value parameters

other: an Ordering to use if this Ordering returns zero

Attributes

Example

case class Pair(a: Int, b: Int)val pairOrdering = Ordering.by[Pair, Int](_.a)                          .orElse(Ordering.by[Pair, Int](_.b))

Source

Ordering.scala

deforElse(other:Ordering[T]):Ordering[T]

Implicitly added byOption

Creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result ofothers compare function.

Value parameters

other: an Ordering to use if this Ordering returns zero

Attributes

Example

case class Pair(a: Int, b: Int)val pairOrdering = Ordering.by[Pair, Int](_.a)                          .orElse(Ordering.by[Pair, Int](_.b))

Source

Ordering.scala

deforElse(other:Ordering[T]):Ordering[T]

Creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result ofothers compare function.

Value parameters

other: an Ordering to use if this Ordering returns zero

Attributes

Example

case class Pair(a: Int, b: Int)val pairOrdering = Ordering.by[Pair, Int](_.a)                          .orElse(Ordering.by[Pair, Int](_.b))

Source

Ordering.scala

deforElseBy[S](f:T=>S)(implicitord:Ordering[S]):Ordering[T]

Implicitly added byIterable

Given f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:

Ordering[S].compare(f(x), f(y))

This function is equivalent to passing the result ofOrdering.by(f) toorElse.

Attributes

Example

case class Pair(a: Int, b: Int)val pairOrdering = Ordering.by[Pair, Int](_.a)                          .orElseBy[Int](_.b)

Source

Ordering.scala

deforElseBy[S](f:T=>S)(implicitord:Ordering[S]):Ordering[T]

Implicitly added byOption

Given f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:

Ordering[S].compare(f(x), f(y))

This function is equivalent to passing the result ofOrdering.by(f) toorElse.

Attributes

Example

case class Pair(a: Int, b: Int)val pairOrdering = Ordering.by[Pair, Int](_.a)                          .orElseBy[Int](_.b)

Source

Ordering.scala

deforElseBy[S](f:T=>S)(implicitord:Ordering[S]):Ordering[T]

Given f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:

Ordering[S].compare(f(x), f(y))

This function is equivalent to passing the result ofOrdering.by(f) toorElse.

Attributes

Example

case class Pair(a: Int, b: Int)val pairOrdering = Ordering.by[Pair, Int](_.a)                          .orElseBy[Int](_.b)

Source

Ordering.scala

overridedefreverse:Ordering[T]

Return the opposite ordering of this one.

Implementations overriding this method MUST overrideisReverseOf as well if they change the behavior at all (for example, caching does not require overriding it).