Spark User Defined Functions

   

·        Write UDFs with a single DataFrame column inputs

·        Transform data using UDFs using both the DataFrame and SQL API

·        Analyze the performance trade-offs between built-in functions and UDFs

How to register UDF?

Python user-defined function (UDF) example:

def squared(s):

  return s * s

spark.udf.register("squaredWithPython", squared)

How to invoke UDF?

spark.range(1, 20).registerTempTable("test")

from pyspark.sql.functions import udf

from pyspark.sql.types import LongType

squared_udf = udf(squared, LongType())

df = spark.table("test")

display(df.select("id", squared_udf("id").alias("id_squared")))