org.saddle.index.ReIndexer

We often need to "reindex" one array/vec/series/frame so as to produce a new one.

First, note that an array A of values of type T is actually a mapping defined as

                f
  [0, A.length) => {T}

That is, each integer index of the array yields a value of type T when it is de-referenced.

ReIndexer has two fields, lTake and rTake, which are array-based maps defined for some integers M and N as

         g
  [0, N) => [-1, M)

In other words, lTake and rTake are arrays of length N whose entries are integers between -1 and M-1. We call these "indexers".

Given a reindexer, g, a re-indexing operation on array A yields a new array B of length N which represents the following mapping:

          B
  [0, N)  =>  {T}

  where B(i) == f(g(i)) if g(i) != -1
             == NA      if g(i) == -1

For this to work, the maximum value M in the co-domain of g must be <= A.length. We also augment the mapping f to send -1 to the corresponding NA value of type T.

For example, suppose we have Index(0,1,2,4) and Index(0,1,2,3). Performing a full outer join would yield the following ReIndexer:

lTake = {0, 1, 2, -1, 3},
rTake = {0, 1, 2, 3, -1},
index = Index(0, 1, 2, 3, 4).

These indexers are then amenable to using with org.saddle.array.take to select elements out of an indexed data structure.

A performance optimization is to make lTake and rTake of type Option[Array], where we make a value of None behave as if it were an array of [0, N). So, the "taking" code knows to take the original values. You will therefore see code that looks like:

  val v = Vec(...)
  val ixer = ReIndexer(...)
  ixer.lTake.map(x => v.take(x)) getOrElse v

Linear Supertypes

AnyRef, Any

Abstract Value Members

abstract def index: Index[T]

The new index
abstract def lTake: Option[Array[Int]]

Offsets into left index corresponding to new index
abstract def rTake: Option[Array[Int]]

Offsets into right index corresponding to new index

Concrete Value Members

final def !=(arg0: AnyRef): Boolean

Definition Classes
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final def !=(arg0: Any): Boolean

Definition Classes
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final def ##(): Int

Definition Classes
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final def ==(arg0: AnyRef): Boolean

Definition Classes
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final def ==(arg0: Any): Boolean

Definition Classes
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final def asInstanceOf[T0]: T0

Definition Classes
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def clone(): AnyRef

Attributes
protected[lang]
Definition Classes
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Annotations
@throws()
final def eq(arg0: AnyRef): Boolean

Definition Classes
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def equals(arg0: Any): Boolean

Definition Classes
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def finalize(): Unit

Attributes
protected[lang]
Definition Classes
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Annotations
@throws()
final def getClass(): java.lang.Class[_]

Definition Classes
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def hashCode(): Int

Definition Classes
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final def isInstanceOf[T0]: Boolean

Definition Classes
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final def ne(arg0: AnyRef): Boolean

Definition Classes
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final def notify(): Unit

Definition Classes
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final def notifyAll(): Unit

Definition Classes
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def swap: ReIndexer[T]

Return ReIndexer with lTake and rTake swapped
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
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def toString(): String

Definition Classes
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final def wait(): Unit

Definition Classes
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Annotations
@throws()
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
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Annotations
@throws()
final def wait(arg0: Long): Unit

Definition Classes
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Annotations
@throws()

ReIndexer

trait ReIndexer[T] extends AnyRef

Abstract Value Members

abstract def index: Index[T]

abstract def lTake: Option[Array[Int]]

abstract def rTake: Option[Array[Int]]

Concrete Value Members

final def !=(arg0: AnyRef): Boolean

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: AnyRef): Boolean

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): java.lang.Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

def swap: ReIndexer[T]

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

Inherited from AnyRef

Inherited from Any