Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Mount the downloaded WebStorm-10*.dmg disk image file as another disk in your system."

A block of code is set as follows:

test("Should use immutable DF API") {
    import spark.sqlContext.implicits._
    //given
    val userData =
        spark.sparkContext.makeRDD(List(
            UserData("a", "1"),
            UserData("b", "2"),
            UserData("d", "200")
        )).toDF()

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

class ImmutableRDD extends FunSuite {
    val spark: SparkContext = SparkSession
        .builder().master("local[2]").getOrCreate().sparkContext

test("RDD should be immutable") {
    //given
    val data = spark.makeRDD(0 to 5)

Any command-line input or output is written as follows:

total_duration/(normal_data.count())

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Select System info from the Administration panel."