Class

org.graphframes.lib

PageRank

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class PageRank extends Arguments

PageRank algorithm implementation. There are two implementations of PageRank.

The first implementation uses the standalone GraphFrame interface and runs PageRank for a fixed number of iterations. This can be run by setting maxIter.

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. This can be run by setting tol.

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:

The resulting edges DataFrame contains one additional column:

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  1. final def !=(arg0: Any): Boolean

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  2. final def ##(): Int

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  3. def +(other: String): String

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    Implicit information
    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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  5. final def ==(arg0: Any): Boolean

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  6. final def asInstanceOf[T0]: T0

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  7. def clone(): AnyRef

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  8. def ensuring(cond: (PageRank) ⇒ Boolean, msg: ⇒ Any): PageRank

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    This member is added by an implicit conversion from PageRank to Ensuring[PageRank] performed by method Ensuring in scala.Predef.
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  9. def ensuring(cond: (PageRank) ⇒ Boolean): PageRank

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    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

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    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

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    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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  14. def finalize(): Unit

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  15. 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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  16. final def getClass(): Class[_]

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  18. final def isInstanceOf[T0]: Boolean

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  19. def maxIter(value: Int): PageRank.this.type

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  20. final def ne(arg0: AnyRef): Boolean

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  21. final def notify(): Unit

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  22. final def notifyAll(): Unit

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  23. def resetProbability(value: Double): PageRank.this.type

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    Reset probability "alpha"

  24. def run(): GraphFrame

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  25. def sourceId(value: Any): PageRank.this.type

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    Source vertex for a Personalized Page Rank (optional)

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

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  27. def toString(): String

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  28. def tol(value: Double): PageRank.this.type

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  29. final def wait(): Unit

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

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  31. final def wait(arg0: Long): Unit

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  32. def [B](y: B): (PageRank, B)

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    Implicit information
    This member is added by an implicit conversion from PageRank to ArrowAssoc[PageRank] performed by method ArrowAssoc in scala.Predef.
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Inherited from Arguments

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Inherited from Any

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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