QualityStats (Lucene 3.6.2 API)
Keywords: org.apache.lucene.benchmark.quality.QualityStats class

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## org.apache.lucene.benchmark.quality
Class QualityStats

    java.lang.Object
      org.apache.lucene.benchmark.quality.QualityStats

    public class QualityStats

extends Object

Results of quality benchmark run for a single query or for a set of queries.

Nested Class Summary
`static class` | `QualityStats.RecallPoint` A certain rank in which a relevant doc was found.

Field Summary
`static int` | `MAX_POINTS` Number of points for which precision is computed.

Constructor Summary
`QualityStats(double maxGoodPoints, long searchTime)` Construct a QualityStats object with anticipated maximal number of relevant hits.

Method Summary
`void` | `addResult(int n, boolean isRelevant, long docNameExtractTime)` Add a (possibly relevant) doc.
`static QualityStats` | `average(QualityStats[] stats)` Create a QualityStats object that is the average of the input QualityStats objects.
`double` | `getAvp()` Return the average precision at recall points.
`long` | `getDocNamesExtractTime()` Returns the time it took to extract doc names for judging the measured query, in milliseconds.
`double` | `getMaxGoodPoints()` Returns the maximal number of good points.
`double` | `getMRR()` Returns the Mean reciprocal rank over the queries or RR for a single query.
`double` | `getNumGoodPoints()` Returns the number of good points (only relevant points).
`double` | `getNumPoints()` Returns the number of points (both relevant and irrelevant points).
`double` | `getPrecisionAt(int n)` Return the precision at rank n: |{relevant hits within first `n` hits}| / `n`.
`double` | `getRecall()` Return the recall: |{relevant hits found}| / |{relevant hits existing}|.
`QualityStats.RecallPoint[]` | `getRecallPoints()` Returns the recallPoints.
`long` | `getSearchTime()` Returns the search time in milliseconds for the measured query.
`void` | `log(String title, int paddLines, PrintWriter logger, String prefix)` Log information on this QualityStats object.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### MAX_POINTS

    public static final int MAX_POINTS

  Number of points for which precision is computed.

  See Also:
    Constant Field Values

Constructor Detail

### QualityStats

    public QualityStats(double maxGoodPoints,
                        long searchTime)

  Construct a QualityStats object with anticipated maximal number of relevant hits.

  Parameters:
    `maxGoodPoints` - maximal possible relevant hits.

Method Detail

### addResult

    public void addResult(int n,
                          boolean isRelevant,
                          long docNameExtractTime)

  Add a (possibly relevant) doc.

  Parameters:
    `n` - rank of the added doc (its ordinal position within the query results).
    `isRelevant` - true if the added doc is relevant, false otherwise.

### getPrecisionAt

    public double getPrecisionAt(int n)

  Return the precision at rank n: |{relevant hits within first `n` hits}| / `n`.

  Parameters:
    `n` - requested precision point, must be at least 1 and at most `MAX_POINTS`.

### getAvp

    public double getAvp()

  Return the average precision at recall points.

### getRecall

    public double getRecall()

  Return the recall: |{relevant hits found}| / |{relevant hits existing}|.

### log

    public void log(String title,
                    int paddLines,
                    PrintWriter logger,
                    String prefix)

  Log information on this QualityStats object.

  Parameters:
    `logger` - Logger.
    `prefix` - prefix before each log line.

### average

    public static QualityStats average(QualityStats[] stats)

  Create a QualityStats object that is the average of the input QualityStats objects.

  Parameters:
    `stats` - array of input stats to be averaged.
  Returns:
    an average over the input stats.

### getDocNamesExtractTime

    public long getDocNamesExtractTime()

  Returns the time it took to extract doc names for judging the measured query, in milliseconds.

### getMaxGoodPoints

    public double getMaxGoodPoints()

  Returns the maximal number of good points. This is the number of relevant docs known by the judge for the measured query.

### getNumGoodPoints

    public double getNumGoodPoints()

  Returns the number of good points (only relevant points).

### getNumPoints

    public double getNumPoints()

  Returns the number of points (both relevant and irrelevant points).

### getRecallPoints

    public QualityStats.RecallPoint[] getRecallPoints()

  Returns the recallPoints.

### getMRR

    public double getMRR()

  Returns the Mean reciprocal rank over the queries or RR for a single query.

  Reciprocal rank is defined as `1/r` where `r` is the rank of the first correct result, or `0` if there are no correct results within the top 5 results.

  This follows the definition in Question Answering - CNLP at the TREC-10 Question Answering Track.

### getSearchTime

    public long getSearchTime()

  Returns the search time in milliseconds for the measured query.

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