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java.lang.Objectorg.apache.mahout.cf.taste.impl.recommender.slopeone.file.FileDiffStorage
public final class FileDiffStorage
DiffStorage
which reads pre-computed diffs from a file and stores in memory. The file should have
one diff per line:
itemID1,itemID2,diff
Commas or tabs can be delimiters. This is intended for use in conjuction with the output of
SlopeOneAverageDiffsJob
.
Constructor Summary | |
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FileDiffStorage(java.io.File dataFile,
long maxEntries)
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Method Summary | |
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RunningAverage |
getAverageItemPref(long itemID)
|
RunningAverage |
getDiff(long itemID1,
long itemID2)
|
RunningAverage[] |
getDiffs(long userID,
long itemID,
PreferenceArray prefs)
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FastIDSet |
getRecommendableItemIDs(long userID)
|
void |
refresh(java.util.Collection<Refreshable> alreadyRefreshed)
Triggers "refresh" -- whatever that means -- of the implementation. |
void |
updateItemPref(long itemID,
float prefDelta,
boolean remove)
Updates internal data structures to reflect an update in a preference value for an item. |
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 FileDiffStorage(java.io.File dataFile, long maxEntries) throws java.io.FileNotFoundException
dataFile
- diffs filemaxEntries
- maximum number of diffs to store
java.io.FileNotFoundException
- if data file does not exist or is a directoryMethod Detail |
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public RunningAverage getDiff(long itemID1, long itemID2)
getDiff
in interface DiffStorage
RunningAverage
encapsulating the average difference in preferences between items
corresponding to itemID1
and itemID2
, in that direction; that is, it's
the average of item 2's preferences minus item 1's preferencespublic RunningAverage[] getDiffs(long userID, long itemID, PreferenceArray prefs)
getDiffs
in interface DiffStorage
userID
- user ID to get diffs foritemID
- itemID to assessprefs
- user's preferendces
RunningAverage
s for that user's item-item diffspublic RunningAverage getAverageItemPref(long itemID)
getAverageItemPref
in interface DiffStorage
RunningAverage
encapsulating the average preference for the given itempublic void updateItemPref(long itemID, float prefDelta, boolean remove)
DiffStorage
Updates internal data structures to reflect an update in a preference value for an item.
updateItemPref
in interface DiffStorage
itemID
- item to update preference value forprefDelta
- amount by which preference value changed (or its old value, if being removedremove
- if true
, operation reflects a removal rather than change of preferencepublic FastIDSet getRecommendableItemIDs(long userID)
getRecommendableItemIDs
in interface DiffStorage
public void refresh(java.util.Collection<Refreshable> alreadyRefreshed)
Refreshable
Triggers "refresh" -- whatever that means -- of the implementation. The general contract is that any 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
- s that are known to have already been
refreshed as a result of an initial call to a method on some
object. This ensure that objects in a refresh dependency graph aren't refreshed twice
needlessly.
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