Mastering Machine Learning with Spark 2.x

Exploring data

The first step involves data load. In the case of multiple files, the SparkContext's method wholeTextFiles provides the functionality we need. It reads each file as a single record and returns it as a key-value pair, where the key contains the location of the file and the value holds the file content. We can reference input files directly via the wildcard pattern data/subject*. This is not only useful during loading files from a local filesystem but especially important for loading files from HDFS as well.

val path = s"${sys.env.get("DATADIR").getOrElse("data")}/subject*"val dataFiles = sc.wholeTextFiles(path)println(s"Number of input files: ${dataFiles.count}")

Since the names are not part of the input data, we define a variable ...