PageRank

PageRank algorithm implementation. There are two implementations of PageRank implemented.

The first implementation uses the Pregel interface and runs PageRank for a fixed number of iterations:

var PR = Array.fill(n)( 1.0 )
val oldPR = Array.fill(n)( 1.0 )
for( iter <- 0 until numIter ) {
  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 standalone Graph interface and runs PageRank until convergence:

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 whick 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.

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def run[VD, ED](graph: Graph[VD, ED], numIter: Int, resetProb: Double = 0.15)(implicit arg0: ClassTag[VD], arg1: ClassTag[ED]): Graph[Double, Double]

Run PageRank for a fixed number of iterations returning a graph with vertex attributes containing the PageRank and edge attributes the normalized edge weight.
Run PageRank for a fixed number of iterations returning a graph with vertex attributes containing the PageRank and edge attributes the normalized edge weight.
VD
the original vertex attribute (not used)
ED
the original edge attribute (not used)
graph
the graph on which to compute PageRank
numIter
the number of iterations of PageRank to run
resetProb
the random reset probability (alpha)
returns
the graph containing with each vertex containing the PageRank and each edge containing the normalized weight.
def runUntilConvergence[VD, ED](graph: Graph[VD, ED], tol: Double, resetProb: Double = 0.15)(implicit arg0: ClassTag[VD], arg1: ClassTag[ED]): Graph[Double, Double]

Run a dynamic version of PageRank returning a graph with vertex attributes containing the PageRank and edge attributes containing the normalized edge weight.
Run a dynamic version of PageRank returning a graph with vertex attributes containing the PageRank and edge attributes containing the normalized edge weight.
VD
the original vertex attribute (not used)
ED
the original edge attribute (not used)
graph
the graph on which to compute PageRank
tol
the tolerance allowed at convergence (smaller => more accurate).
resetProb
the random reset probability (alpha)
returns
the graph containing with each vertex containing the PageRank and each edge containing the normalized weight.
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object PageRank extends Logging

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final def !=(arg0: AnyRef): Boolean

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: AnyRef): Boolean

final def ==(arg0: Any): Boolean

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def log: Logger

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def logDebug(msg: ⇒ String): Unit

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def logWarning(msg: ⇒ String, throwable: Throwable): Unit

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def run[VD, ED](graph: Graph[VD, ED], numIter: Int, resetProb: Double = 0.15)(implicit arg0: ClassTag[VD], arg1: ClassTag[ED]): Graph[Double, Double]

def runUntilConvergence[VD, ED](graph: Graph[VD, ED], tol: Double, resetProb: Double = 0.15)(implicit arg0: ClassTag[VD], arg1: ClassTag[ED]): Graph[Double, Double]

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

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