Welcome to Cascading for the Impatient, a tutorial for Cascading 2.2 to get you started. Quickly. Like, yesterday.
This set of progressive coding examples starts with a simple file copy and builds up to a MapReduce implementation of the TF-IDF algorithm.
You can read the full series here: http://docs.cascading.org/impatient/
If you have a question or run into any problems send an email to the cascading-user-list.
- Implements simplest Cascading app possible
- Copies each TSV line from source tap to sink tap
- Roughly, in about a dozen lines of code
- Physical plan: 1 Mapper
- Implements a simple example of WordCount
- Uses a regex to split the input text lines into a token stream
- Generates a DOT file, to show the Cascading flow graphically
- Physical plan: 1 Mapper, 1 Reducer
- Uses a custom Function to scrub the token stream
- Discusses when to use standard Operations vs. creating custom ones
- Physical plan: 1 Mapper, 1 Reducer
- Shows how to use a HashJoin on two pipes
- Filters a list of stop words out of the token stream
- Physical plan: 1 Mapper, 1 Reducer
- Calculates TF-IDF using an ExpressionFunction
- Shows how to use a CountBy, SumBy, and a CoGroup
- Physical plan: 10 Mappers, 8 Reducers
- Includes unit tests in the build
- Shows how to use other TDD features: checkpoints, assertions, traps, debug
- Physical plan: 11 Mappers, 8 Reducers
- Implements switch to run the example in local mode (without Apache Hadoop)
- Uses an R script to analyze/visualize the results
- Scalding equivalents of previous examples in Cascading