⚠️Warning: The library is still in alpha, and it is not fully tested.

deequ.NET is a port of the awslabs/deequ library built on top of Apache Spark for defining "unit tests for data", which measure data quality in large datasets. deequ.NET runs on dotnet/spark.

deequ.NET runs on Apache Spark and depends on dotnet/spark. Therefore it is required to install the following dependencies locally:

• .NET Core 3.1 SDK
• OpenJDK 8
• Apache Spark 2.3 +

It is also necessary to install the Microsoft.Spark.Worker on your local machine and configure the path into the PATH env var. For a detailed instructions, see dotnet/spark - Getting started

The following example implements a set of checks on some records and it submits the execution using the spark-submit command.

• Use the dotnet CLI to create a console application:

  dotnet new console -o DeequExample

• Install Microsoft.Spark and the deequ Nuget packages into the project:

  cd DeequExample
  
  dotnet add package Microsoft.Spark
  dotnet add package deequ

• Replace the contents of the Program.cs file with the following code:

  using deequ;
  using deequ.Checks;
  using deequ.Extensions;
  using Microsoft.Spark.Sql;
  
  namespace DeequExample
  {
      class Program
      {
          static void Main(string[] args)
          {
              SparkSession spark = SparkSession.Builder().GetOrCreate();
              DataFrame data = spark.Read().Json("inventory.json");
  
              data.Show();
  
              VerificationResult verificationResult = new VerificationSuite()
                  .OnData(data)
                  .AddCheck(
                      new Check(CheckLevel.Error, "integrity checks")
                          .HasSize(value => value == 5)
                          .IsComplete("id")
                          .IsUnique("id")
                          .IsComplete("productName")
                          .IsContainedIn("priority", new[] { "high", "low" })
                          .IsNonNegative("numViews")
                  )
                  .AddCheck(
                      new Check(CheckLevel.Warning, "distribution checks")
                          .ContainsURL("description", value => value >= .5)
                  )
                  .Run();
  
              verificationResult.Debug();
          }
      }
  }

• Use the dotnet CLI to build the application:

  dotnet build

• Open your terminal and navigate into your app folder.

  cd <your-app-output-directory>

• Create inventory.json with the following content:

  {"id":1, "productName":"Thingy A", "description":"awesome thing. http://thingb.com", "priority":"high", "numViews":0}
  {"id":2, "productName":"Thingy B", "description":"available at http://thingb.com","priority":null, "numViews":0}
  {"id":3, "productName":"Thingy C", "description": null, "priority":"low", "numViews":5}
  {"id":4, "productName":"Thingy D", "description": "checkout https://thingd.ca", "priority":"low","numViews": 10}
  {"id":5, "productName":"Thingy E", "description":null, "priority":"high","numViews": 12}

• Run your app.

  spark-submit \
      --class org.apache.spark.deploy.dotnet.DotnetRunner \
      --master local \
      microsoft-spark-2.4.x-<version>.jar \
  dotnet DeequExample.dll

  Note: This command requires Apache Spark in your PATH environment variable to be able to use spark-submit. For detailed instructions, you can see Building .NET for Apache Spark from Source on Ubuntu.

• The output of the application should look similar to the output below:

  
       _                         _   _ ______ _______
      | |                       | \ | |  ____|__   __|
    __| | ___  ___  __ _ _   _  |  \| | |__     | |
   / _` |/ _ \/ _ \/ _` | | | | | . ` |  __|    | |
  | (_| |  __/  __/ (_| | |_| |_| |\  | |____   | |
   \__,_|\___|\___|\__, |\__,_(_)_| \_|______|  |_|
                      | |
                      |_|
  
  
  
  Success
  

The following list shows more examples/showcases of the deequ.NET API:

• Incremental metrics computation
• Anomaly detection

• awslabs/deequ
• dotnet/spark
• akkadotnet/akka.net - Scala to C# conversion guide

Sebastian Schelter, Dustin Lange, Philipp Schmidt, Meltem Celikel, Felix Biessmann, and Andreas Grafberger. 2018. Automating large-scale data quality verification. Proc. VLDB Endow. 11, 12 (August 2018), 1781-1794.