Github user liancheng commented on a diff in the pull request:
https://github.com/apache/spark/pull/12088#discussion_r58096567
--- Diff:
mllib/src/main/scala/org/apache/spark/ml/source/libsvm/LibSVMRelation.scala ---
@@ -127,6 +135,32 @@ class DefaultSource extends FileFormat with
DataSourceRegister {
StructField("features", new VectorUDT(), nullable = false) :: Nil))
}
+ override def prepareRead(
+ sqlContext: SQLContext,
+ options: Map[String, String],
+ files: Seq[FileStatus]): Map[String, String] = {
+ def computeNumFeatures(): Int = {
+ val dataFiles = files.filterNot(_.getPath.getName startsWith "_")
+ val path = if (dataFiles.length == 1) {
+ dataFiles.head.getPath.toUri.toString
+ } else if (dataFiles.isEmpty) {
+ throw new IOException("No input path specified for libsvm data")
+ } else {
+ throw new IOException("Multiple input paths are not supported for
libsvm data.")
+ }
+
+ val sc = sqlContext.sparkContext
+ val parsed = MLUtils.parseLibSVMFile(sc, path, sc.defaultParallelism)
+ MLUtils.computeNumFeatures(parsed)
--- End diff --
Note that unlike what we do in `MLUtils`, we don't cache `parsed` RDD here
since it's constructed using different partitioning strategies as the final
`FileScanRDD`. This is a potential performance regression.
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