JarCastingspark-daria
Spark helper methods to maximize developer productivity.
CI: 
Code quality:
Setup
Fetch the JAR file from Maven.
// Spark 3
libraryDependencies += "com.github.mrpowers" %% "spark-daria" % "1.0.0"
// Spark 2
libraryDependencies += "com.github.mrpowers" %% "spark-daria" % "0.39.0"
You can find the spark-daria Scala 2.11 versions here and the Scala 2.12 versions here. The legacy versions are here.
Writing Beautiful Spark Code
Reading Beautiful Spark Code is the best way to learn how to build Spark projects and leverage spark-daria.
spark-daria will make you a more productive Spark programmer. Studying the spark-daria codebase will help you understand how to organize Spark codebases.
PySpark
Use quinn to access similar functions in PySpark.
Usage
spark-daria provides different types of functions that will make your life as a Spark developer easier:
- Core extensions
- Column functions / UDFs
- Custom transformations
- Helper methods
- DataFrame validators
The following overview will give you an idea of the types of functions that are provided by spark-daria, but you'll need to dig into the docs to learn about all the methods.
Core extensions
The core extensions add methods to existing Spark classes that will help you write beautiful code.
The native Spark API forces you to write code like this.
col("is_nice_person").isNull && col("likes_peanut_butter") === false
When you import the spark-daria ColumnExt class, you can write idiomatic Scala code like this:
import com.github.mrpowers.spark.daria.sql.ColumnExt._
col("is_nice_person").isNull && col("likes_peanut_butter").isFalse
This blog post describes how to use the spark-daria createDF() method that's much better than the toDF() and createDataFrame() methods provided by Spark.
See the ColumnExt, DataFrameExt, and SparkSessionExt objects for all the core extensions offered by spark-daria.
Column functions
Column functions can be used in addition to the org.apache.spark.sql.functions.
Here is how to remove all whitespace from a string with the native Spark API:
import org.apache.spark.sql.functions._
regexp_replace(col("first_name"), "\\s+", "")
The spark-daria removeAllWhitespace() function lets you express this logic with code that's more readable.
import com.github.mrpowers.spark.daria.sql.functions._
removeAllWhitespace(col("first_name"))
Datetime functions
beginningOfWeekendOfWeekbeginningOfMonthendOfMonth
Custom transformations
Custom transformations have the following method signature so they can be passed as arguments to the Spark DataFrame#transform() method.
def someCustomTransformation(arg1: String)(df: DataFrame): DataFrame = {
// code that returns a DataFrame
}
The spark-daria snakeCaseColumns() custom transformation snake_cases all of the column names in a DataFrame.
import com.github.mrpowers.spark.daria.sql.transformations._
val betterDF = df.transform(snakeCaseColumns())
Protip: You'll always want to deal with snake_case column names in Spark - use this function if your column names contain spaces of uppercase letters.
Helper methods
The DataFrame helper methods make it easy to convert DataFrame columns into Arrays or Maps. Here's how to convert a column to an Array.
import com.github.mrpowers.spark.daria.sql.DataFrameHelpers._
val arr = columnToArray[Int](sourceDF, "num")
DataFrame validators
DataFrame validators check that DataFrames contain certain columns or a specific schema. They throw descriptive error messages if the DataFrame schema is not as expected. DataFrame validators are a great way to make sure your application gives descriptive error messages.
Let's look at a method that makes sure a DataFrame contains the expected columns.
val sourceDF = Seq(
("jets", "football"),
("nacional", "soccer")
).toDF("team", "sport")
val requiredColNames = Seq("team", "sport", "country", "city")
validatePresenceOfColumns(sourceDF, requiredColNames)
// throws this error message: com.github.mrpowers.spark.daria.sql.MissingDataFrameColumnsException: The [country, city] columns are not included in the DataFrame with the following columns [team, sport]
Documentation
Here is the latest spark-daria documentation.
Studying these docs will make you a better Spark developer!
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Contribution Criteria
We are actively looking for contributors to add functionality that fills in the gaps of the Spark source code.
To get started, fork the project and submit a pull request. Please write tests!
After submitting a couple of good pull requests, you'll be added as a contributor to the project.
Publishing
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Version bump commit and create GitHub tag
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Publish documentation with
sbt ghpagesPushSite -
Publish JAR
Run sbt to open the SBT console.
Run > ; + publishSigned; sonatypeBundleRelease to create the JAR files and release them to Maven. These commands are made available by the sbt-sonatype plugin.
When the release command is run, you'll be prompted to enter your GPG passphrase.
The Sonatype credentials should be stored in the ~/.sbt/sonatype_credentials file in this format:
realm=Sonatype Nexus Repository Manager
host=oss.sonatype.org
user=$USERNAME
password=$PASSWORD