Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
A Scala API for Cascading
Scala Ruby Java Shell

Merge pull request #1232 from twitter/klin_klist_unique

Add distinctCount and distinctValues helper methods to KeyedList.
latest commit b3fd74c488
@johnynek johnynek authored
Failed to load latest commit information.
logo Add scalding logo
maple/src/main/java/com Revert hack in TupleMemoryInputFormat
project Add sorting benchmarks
scalding-args/src Override hashCode for Args
scalding-avro Move Scalding to 2.10/2.11
scalding-benchmarks/src/test/scala/com/twitter/scalding Remove equality checking
scalding-commons Covert LzoTextDelimited to Cascading scheme.
scalding-core Also update distinctValues.
scalding-date/src Add an exclusiveUpper method to DateRange
scalding-hadoop-test/src Commit non-macro ordered-serialization
scalding-hraven only request necessary hadoop configs in hraven reducer estimator
scalding-jdbc/src Fixes
scalding-json/src Easy split off portion from the macro PR
scalding-macros/src Address Alex's comments
scalding-parquet-scrooge Add parquet-scrooge sources
scalding-parquet Fix compile errors in tests
scalding-repl Add dump to ValuePipe in the REPL
scripts Use shell to read scala and scalding versions.
tutorial Partial of Oscar and Alex's comments.
.gitignore Put the hadoop notice file into the git ignore
.travis.yml Add the macros for OrderedSerialization
CHANGES.md Prepare for release of 0.13.1
CONTRIBUTING.md Add CONTRIBUTING.md
LICENSE Initial Import
NOTICE Initial Import
README.md Add jonathan.
sbt Try sudo off again, and use https for sbt repo
version.sbt Prepare for release of 0.13.1

README.md

Scalding

Scalding is a Scala library that makes it easy to specify Hadoop MapReduce jobs. Scalding is built on top of Cascading, a Java library that abstracts away low-level Hadoop details. Scalding is comparable to Pig, but offers tight integration with Scala, bringing advantages of Scala to your MapReduce jobs.

Scalding Logo

Current version: 0.13.1

Word Count

Hadoop is a distributed system for counting words. Here is how it's done in Scalding.

package com.twitter.scalding.examples

import com.twitter.scalding._

class WordCountJob(args: Args) extends Job(args) {
  TypedPipe.from(TextLine(args("input")))
    .flatMap { line => tokenize(line) }
    .groupBy { word => word } // use each word for a key
    .size // in each group, get the size
    .write(TypedTsv[(String, Long)](args("output")))

  // Split a piece of text into individual words.
  def tokenize(text : String) : Array[String] = {
    // Lowercase each word and remove punctuation.
    text.toLowerCase.replaceAll("[^a-zA-Z0-9\\s]", "").split("\\s+")
  }
}

Notice that the tokenize function, which is standard Scala, integrates naturally with the rest of the MapReduce job. This is a very powerful feature of Scalding. (Compare it to the use of UDFs in Pig.)

You can find more example code under examples/. If you're interested in comparing Scalding to other languages, see our Rosetta Code page, which has several MapReduce tasks in Scalding and other frameworks (e.g., Pig and Hadoop Streaming).

Documentation and Getting Started

Please feel free to use the beautiful Scalding logo artwork anywhere.

Code of Conduct

This, and all github.com/twitter projects, are under the Twitter Open Source Code of Conduct. Additionally, see the Typelevel Code of Conduct for specific examples of harassing behavior that are not tolerated.

Building

There is a script (called sbt) in the root that loads the correct sbt version to build:

  1. ./sbt update (takes 2 minutes or more)
  2. ./sbt test
  3. ./sbt assembly (needed to make the jar used by the scald.rb script)

The test suite takes a while to run. When you're in sbt, here's a shortcut to run just one test:

> test-only com.twitter.scalding.FileSourceTest

Please refer to FAQ page if you encounter problems when using sbt.

We use Travis CI to verify the build: Build Status

We use Coveralls for code coverage results: Coverage Status

Scalding modules are available from maven central.

The current groupid and version for all modules is, respectively, "com.twitter" and 0.12.0.

Current published artifacts are

  • scalding-core_2.10
  • scalding-args_2.10
  • scalding-date_2.10
  • scalding-commons_2.10
  • scalding-avro_2.10
  • scalding-parquet_2.10
  • scalding-repl_2.10

The suffix denotes the scala version.

Adopters

  • Ebay
  • Etsy
  • Sharethrough
  • Snowplow Analytics
  • Soundcloud
  • Twitter

To see a full list of users or to add yourself, see the wiki

Contact

For user questions, we are using the cascading-user mailing list for discussions: http://groups.google.com/group/cascading-user

For scalding development (internals, extending, release planning): https://groups.google.com/forum/#!forum/scalding-dev

In the remote possibility that there exist bugs in this code, please report them to: https://github.com/twitter/scalding/issues

Follow @Scalding on Twitter for updates.

Chat (IRC): freenode channel: #scalding

Authors:

Thanks for assistance and contributions:

A full list of contributors can be found on GitHub.

License

Copyright 2013 Twitter, Inc.

Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0

Something went wrong with that request. Please try again.