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Cascalog for the Impatient

Welcome to Cascalog for the Impatient, a series of blog posts and Cascalog code examples to get you started. Quickly. Like, yesterday.

Use this tutorial in conjunction with Cascading for the Impatient.

Part 1

• Implements simplest Cascading app possible
• Copies each TSV line from source tap to sink tap
• Roughly, in about a dozen lines of code

Part 2

• Implements a simple example of WordCount
• Uses a regex to split the input text lines into a token stream

Part 3

• Uses a custom Function to scrub the token stream
• Discusses when to use standard Operations vs. creating custom ones

Part 4

• Shows how to use a HashJoin on two pipes
• Filters a list of stop words out of the token stream

Part 5

• Calculates TF-IDF using an ExpressionFunction
• Shows how to use a SumBy and a CoGroup

Part 6

• Includes unit tests in the build
• Shows how to use other TDD features: checkpoints, assertions, traps, debug

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If you want to read in more detail about the Cascalog API which were used, see the Cascalog Wiki and JavaDoc.

For more discussion, see the cascalog-user email forum.