Raymond Raymond | Code Snippets & Tips

Convert List to Spark Data Frame in Scala / Spark

event 2019-11-18 visibility 24,876 comment 0 insights toc
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In Spark, SparkContext.parallelize function can be used to convert list of objects to RDD and then RDD can be converted to DataFrame object through SparkSession.

Similar to PySpark, we can use SparkContext.parallelize function to create RDD; alternatively we can also use SparkContext.makeRDD function to convert list to RDD.

The output looks like the following:

+----------+-----+------------------+
|  Category|Count|       Description|
+----------+-----+------------------+
|Category A|  100|This is category A|
|Category B|  120|This is category B|
|Category C|  150|This is category C|
+----------+-----+------------------+

Code snippet

import org.apache.spark.sql._
import org.apache.spark.sql.types._

val appName = "Scala Example - List to Spark Data Frame"
val master = "local"

/*Create Spark session with Hive supported.*/
val spark = SparkSession.builder.appName(appName).master(master).getOrCreate()

/* List */
val data = List(Row("Category A", 100, "This is category A"),
Row("Category B", 120, "This is category B"),
Row("Category C", 150, "This is category C"))

val schema = StructType(List(
  StructField("Category", StringType, true),
StructField("Count", IntegerType, true),
StructField("Description", StringType, true)
))

/* Convert list to RDD */
val rdd = spark.sparkContext.parallelize(data)

/* Create data frame */
val df = spark.createDataFrame(rdd, schema)
print(df.schema)
df.show()
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