class PageRank extends Arguments

PageRank algorithm implementation. There are two implementations of PageRank.

The first one uses the org.apache.spark.graphx.graph interface with aggregateMessages and runs PageRank for a fixed number of iterations. This can be executed by setting maxIter. Conceptually, the algorithm does the following:

var PR = Array.fill(n)( 1.0 )
val oldPR = Array.fill(n)( 1.0 )
for( iter <- 0 until maxIter ) {
  swap(oldPR, PR)
  for( i <- 0 until n ) {
    PR[i] = alpha + (1 - alpha) * inNbrs[i].map(j => oldPR[j] / outDeg[j]).sum
  }
}

The second implementation uses the org.apache.spark.graphx.Pregel interface and runs PageRank until convergence and this can be run by setting tol. Conceptually, the algorithm does the following:

var PR = Array.fill(n)( 1.0 )
val oldPR = Array.fill(n)( 0.0 )
while( max(abs(PR - oldPr)) > tol ) {
  swap(oldPR, PR)
  for( i <- 0 until n if abs(PR[i] - oldPR[i]) > tol ) {
    PR[i] = alpha + (1 - \alpha) * inNbrs[i].map(j => oldPR[j] / outDeg[j]).sum
  }
}

alpha is the random reset probability (typically 0.15), inNbrs[i] is the set of neighbors which link to i and outDeg[j] is the out degree of vertex j.

Note that this is not the "normalized" PageRank and as a consequence pages that have no inlinks will have a PageRank of alpha. In particular, the pageranks may have some values greater than 1.

The resulting vertices DataFrame contains one additional column:

  • pagerank (DoubleType): the pagerank of this vertex

The resulting edges DataFrame contains one additional column:

  • weight (DoubleType): the normalized weight of this edge after running PageRank
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  2. final def ##(): Int
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  3. def +(other: String): String
    Implicit
    This member is added by an implicit conversion from PageRank to any2stringadd[PageRank] performed by method any2stringadd in scala.Predef.
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    any2stringadd
  4. def ->[B](y: B): (PageRank, B)
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    This member is added by an implicit conversion from PageRank to ArrowAssoc[PageRank] performed by method ArrowAssoc in scala.Predef.
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    @throws( ... ) @native() @HotSpotIntrinsicCandidate()
  8. def ensuring(cond: (PageRank) ⇒ Boolean, msg: ⇒ Any): PageRank
    Implicit
    This member is added by an implicit conversion from PageRank to Ensuring[PageRank] performed by method Ensuring in scala.Predef.
    Definition Classes
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  9. def ensuring(cond: (PageRank) ⇒ Boolean): PageRank
    Implicit
    This member is added by an implicit conversion from PageRank to Ensuring[PageRank] performed by method Ensuring in scala.Predef.
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  10. def ensuring(cond: Boolean, msg: ⇒ Any): PageRank
    Implicit
    This member is added by an implicit conversion from PageRank to Ensuring[PageRank] performed by method Ensuring in scala.Predef.
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  11. def ensuring(cond: Boolean): PageRank
    Implicit
    This member is added by an implicit conversion from PageRank to Ensuring[PageRank] performed by method Ensuring in scala.Predef.
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  12. final def eq(arg0: AnyRef): Boolean
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  16. final def isInstanceOf[T0]: Boolean
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  17. def maxIter(value: Int): PageRank.this.type
  18. final def ne(arg0: AnyRef): Boolean
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  19. final def notify(): Unit
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  20. final def notifyAll(): Unit
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  21. def resetProbability(value: Double): PageRank.this.type

    Reset probability "alpha"

  22. def run(): GraphFrame
  23. def sourceId(value: Any): PageRank.this.type

    Source vertex for a Personalized Page Rank (optional)

  24. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  25. def toString(): String
    Definition Classes
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  26. def tol(value: Double): PageRank.this.type
  27. final def wait(arg0: Long, arg1: Int): Unit
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  28. final def wait(arg0: Long): Unit
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  29. final def wait(): Unit
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  30. def →[B](y: B): (PageRank, B)
    Implicit
    This member is added by an implicit conversion from PageRank to ArrowAssoc[PageRank] performed by method ArrowAssoc in scala.Predef.
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  1. def finalize(): Unit
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  2. def formatted(fmtstr: String): String
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    This member is added by an implicit conversion from PageRank to StringFormat[PageRank] performed by method StringFormat in scala.Predef.
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    @deprecated @inline()
    Deprecated

    (Since version 2.12.16) Use formatString.format(value) instead of value.formatted(formatString), or use the f"" string interpolator. In Java 15 and later, formatted resolves to the new method in String which has reversed parameters.

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Inherited by implicit conversion any2stringadd from PageRank to any2stringadd[PageRank]

Inherited by implicit conversion StringFormat from PageRank to StringFormat[PageRank]

Inherited by implicit conversion Ensuring from PageRank to Ensuring[PageRank]

Inherited by implicit conversion ArrowAssoc from PageRank to ArrowAssoc[PageRank]

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