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java.lang.Objectorg.apache.mahout.cf.taste.impl.similarity.SpearmanCorrelationSimilarity
public final class SpearmanCorrelationSimilarity
Like PearsonCorrelationSimilarity
, but compares relative ranking of preference values instead of
preference values themselves. That is, each user's preferences are sorted and then assign a rank as their
preference value, with 1 being assigned to the least preferred item.
Constructor Summary | |
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SpearmanCorrelationSimilarity(DataModel dataModel)
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Method Summary | |
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void |
refresh(Collection<Refreshable> alreadyRefreshed)
Triggers "refresh" -- whatever that means -- of the implementation. |
void |
setPreferenceInferrer(PreferenceInferrer inferrer)
Attaches a PreferenceInferrer to the UserSimilarity implementation. |
double |
userSimilarity(long userID1,
long userID2)
Returns the degree of similarity, of two users, based on the their preferences. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public SpearmanCorrelationSimilarity(DataModel dataModel)
Method Detail |
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public double userSimilarity(long userID1, long userID2) throws TasteException
UserSimilarity
Returns the degree of similarity, of two users, based on the their preferences.
userSimilarity
in interface UserSimilarity
userID1
- first user IDuserID2
- second user ID
Double.NaN
similarity is unknown
NoSuchUserException
- if either user is known to be non-existent in the data
TasteException
- if an error occurs while accessing the datapublic void setPreferenceInferrer(PreferenceInferrer inferrer)
UserSimilarity
Attaches a PreferenceInferrer
to the UserSimilarity
implementation.
setPreferenceInferrer
in interface UserSimilarity
inferrer
- PreferenceInferrer
public void refresh(Collection<Refreshable> alreadyRefreshed)
Refreshable
Triggers "refresh" -- whatever that means -- of the implementation. The general contract is that any
Refreshable
should always leave itself in a consistent, operational state, and that the refresh
atomically updates internal state from old to new.
refresh
in interface Refreshable
alreadyRefreshed
- Refreshable
s that are known to have already been
refreshed as a result of an initial call to a Refreshable.refresh(Collection)
method on some
object. This ensure that objects in a refresh dependency graph aren't refreshed twice
needlessly.
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