Andrew Palumbo created MAHOUT-1545:
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Summary: Creating holdout sets with seq2sparse and split
Key: MAHOUT-1545
URL: https://issues.apache.org/jira/browse/MAHOUT-1545
Project: Mahout
Issue Type: Bug
Components: Classification, CLI, Examples
Affects Versions: 0.9
Reporter: Andrew Palumbo
The current method for vectorizing data using seq2sparse and then "split"
allows for a large amount of information to spill over from the training sets
to the test sets- especially in the case of TF-IDF transformations. The IDF
transform mainly, but also normalization provide alot of information on the
holdout set to the training set if calculated previous to splitting them up.
I'm not sure if given the current seq2sparse implementation's status as Legacy
and the relatively minor advantages that it might give weather or not its worth
adding something like a "split" option to SparseVectorsFromSequenceFiles.java.
But i know that i saw a new implementation being discussed and and think that
it would be worth it to have an option like this built in.
I think that this issue may have been raised before, but i wanted to bring it
up again in light of the current move away from MapReduce and the new
implementations of Mahout tools that will be coming along.
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