Implementation of Cosine distance measure, plus unit test.
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Key: MAHOUT-109
URL: https://issues.apache.org/jira/browse/MAHOUT-109
Project: Mahout
Issue Type: Improvement
Reporter: Richard Tomsett
Priority: Trivial
This is a class implementing a cosine distance measure. In various places I've
seen cosine *similarity* defined as being the cosine of the angle between
vectors - cos(a,b) - and cosine *distance* being (1 - cos(a,b)), so in keeping
with the other distance measures, this returns 1-cos(angle) as the distance.
Made a new test class rather than using the default distance measure check as
the vectors in the current default test class all have a cosine distance of
zero between them ([1,1,1,1,1,1], [3,3,3,3,3,3] and [6,6,6,6,6,6]). The test
checks the cosine distances between [1,0,0,0,0,0], [1,1,1,0,0,0] and
[1,1,1,1,1,1].
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