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Mahout and Scalding for poker collusion detection

When I’ve been reading a very bright book on Mahout, Mahout In Action (which is a great hands-in intro to machine learning, as well), one of the examples has caught my attention. Authors of the book where using well-known K-means clusterization algorithm for finding similar players on stackoverflow.com, where the criterion of similarity was the set of the authors of ...

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Groovy DSL – A Simple Example

Domain Specific Languages (DSLs) have become a valuable part of the Groovy idiom. DSLs are used in native Groovy builders, Grails and GORM, and testing frameworks. To a developer, DSLs are consumable and understandable, which makes implementation more fluid as compared to traditional programming. But how is a DSL implemented? How does it work behind the scenes? This article will ...

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Custom Ordering Scala TreeMap

How do you get custom ordering in a Scala TreeMap? Well this puzzled me for a while. The answer lies in the world of implicits and receiver type converters. In a nut shell, a scala.collection.immutable.TreeMap is a SortedMap. If you look at the documentation for TreeMap, you will see it takes an Ordering[T] as an implicit argument. Normally when you ...

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Grails Custom AuthenticationProvider

In order to tighten up security in our new Grails app I went about implementing the Spring Security Plugin. Getting it up and running with a standard username/password scenario was simple, as that is all wired up automagically by the plugin. That solved half of my problem, but we also need to support authentication with SAML, and there were no ...

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GitHub Social Graphs with Groovy and GraphViz

The Goal Using the GitHub API, Groovy and GraphViz to determine, interpret and render a graph of the relationships between GitHub users based on the watchers of their repositories. The end result can look something like this. The GitHub V3 API You can find the full documentation for the GitHub V3 API here. They do a great job of documenting ...

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Power with control: Scala control structures and abstractions

So ramping up with the Scala 101 series, I thought now is an appropriate juncture to introduce control structures in Scala. To a certain extent, working with the Scala language presents a vista wherein the developer is afforded much greater freedom than in many other environments, but therein lies a great many choices and a sense of responsibility. As such, ...

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ScaTDD: Casting an eye over three major Test frameworks in Scala

Testing has traditionally been the gateway process for Scala development at a number of Java shops looking to evolve their tech stack with minimal disruption or committment. This posts hopes to cover three of the main testing frameworks in the Scala landscape, ( Specs2, Scalatest and Scalacheck) with an example of the classic FizzBuzz test, for how they can be ...

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Using Groovy scriptlets inside a *.docx document

Introduction One of my recent projects required automated generation of contracts for customers. Contract is a legal document of about 10 pages length. One contract form can be applied for many customers so the document is a template with customer info put in certain places. In this article I am going to show you how I solved this problem. Requirements ...

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A crash course in Scala types

After many years of Java development, discovering Scala’s type system and related features was something of a departure for me. Suffice to say GADT wasn’t my first four letter utterance when learning about pattern matching on types, let alone what, when and how to use variance annotations and generalized type constraints. To kick things off, here’s a ‘small but powerful‘ ...

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