Would you like to make a PR that can be reviewed? Sent from my iPhone
> On Apr 19, 2016, at 4:20 AM, Edmond Luo (JIRA) <[email protected]> wrote: > > Edmond Luo created MAHOUT-1833: > ---------------------------------- > > Summary: One more svec function accepting cardinality as > parameter > Key: MAHOUT-1833 > URL: https://issues.apache.org/jira/browse/MAHOUT-1833 > Project: Mahout > Issue Type: Improvement > Affects Versions: 0.12.0 > Environment: Mahout Spark Shell 0.12.0, > Spark 1.6.0 Cluster on Hadoop Yarn 2.7.1, > Centos7 64bit > Reporter: Edmond Luo > > > It will be nice to add one more wrapper function like below to > org.apache.mahout.math.scalabindings > > {code} > /** > * create a sparse vector out of list of tuple2's with specific > cardinality(size), > * throws IllegalArgumentException if cardinality is not bigger than required > cardinality of sdata > * @param cardinality sdata > * @return > */ > def svec(cardinality: Int, sdata: TraversableOnce[(Int, AnyVal)]) = { > val required = if (sdata.nonEmpty) sdata.map(_._1).max + 1 else 0 > if (cardinality < required) { > throw new IllegalArgumentException(s"Cardinality[%cardinality] must be > bigger than required[%required]!") > } > > val initialCapacity = sdata.size > val sv = new RandomAccessSparseVector(cardinality, initialCapacity) > sdata.foreach(t ⇒ sv.setQuick(t._1, t._2.asInstanceOf[Number].doubleValue())) > sv > } > {code} > > So user can specify the cardinality for the created sparse vector. > > This is very useful and convenient if user wants to create a DRM with many > sparse vectors and the vectors are not with the same actual size(but with the > same logical size, e.g. rows of a sparse matrix). > > Below code should demonstrate the case: > {code} > var cardinality = 20 > val rdd = sc.textFile("/some/file.txt").map(_.split(",")).map(line => > (line(0).toInt, Array((line(1).toInt,1)))).reduceByKey((v1, v2) => v1 ++ > v2).map(row => (row._1, svec(cardinality, row._2))) > > val drm = drmWrap(rdd.map(row => (row._1, row._2.asInstanceOf[Vector]))) > > // All element wise opperation will fail for those DRM with not > cardinality-consistent SparseVector > val drm2 = drm + drm > val drm3 = drm - drm > val drm4 = drm * drm > val drm5 = drm / drm > {code} > > Notice that in the last map, the svec in above accepts one more parameter, so > the cardinality of those created SparseVector can be consistent. > > > > > -- > This message was sent by Atlassian JIRA > (v6.3.4#6332)
