Joshua Hartman created DATAFU-60:
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Summary: Support NDCG calculation within a UDF
Key: DATAFU-60
URL: https://issues.apache.org/jira/browse/DATAFU-60
Project: DataFu
Issue Type: New Feature
Reporter: Joshua Hartman
Ndcg is a common evaluation metric for the quality of a list of items presented
to a user. It is an especially common metric used in the search literature.
This feature request is to implement a udf to calculate ndcg.
NDCG can be calculated using any function to represent the value of a position.
Several useful functions should be available as part of the datafu library.
First is the standard 1/logarithmic discounting factor. Another option should
be the ability to supply a custom positional value for any range of positions
in the case that a positional "value" is already well understood. However, the
actual discounting function used should be easily pluggable in the event
something custom is needed
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