could you be more explicit on your needs? How many documents have your
index, how many different categories are and how much is the average
search hit number would be enough to suggest an approach.
In my case i made an custom collector to count the hits on every
category using a fieldcache item to get the item efficiently instead
of call to hit.getDocument. (performance killer).
this is better if your searches return small sets and you have much
categories.
If you have not many terms, and your searches return many results, you
can use queryfilter.bits to get the masks, AND them, and count the
number of set bits on the result. this have the drawback that .net
implementation of Bitarray, don't have an efficient method of counting
the set bits (cardinality on java), but you could get one from the
bitvector class on lucene.net (you must use you own implementation of
bitarray, or use reflection to access the backbone int32 array m_array
and count over him).
here is the function to get the number of ones set in a bitarray:
Private Shared _bitsSetArray256 As Byte() = {0, 1, 1, 2, 1, 2, 2, 3,
1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4,
5, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4,
4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3,
4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4,
3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5,
6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3,
3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4, 3, 4, 4, 5, 3,
4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5,
6, 4, 5, 5, 6, 5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6,
6, 7, 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8}
''' <summary>
''' return the number of bits on bitarray set to one
''' </summary>
''' <remarks></remarks>
Private Function Cardinality(ByVal bits As BitArray) As Int32
Dim arr As UInt32()
arr = bits.GetType().GetField("m_array",
Reflection.BindingFlags.NonPublic Or
Reflection.BindingFlags.Instance).GetValue(bits)
Dim _count As Int32 = 0
For i As Int32 = 0 To arr.Length - 1
_count += _bitsSetArray256(arr(i) And &HFF) + _
_bitsSetArray256((arr(i) >> 8) And &HFF) + _
_bitsSetArray256((arr(i) >> 16) And &HFF) + _
_bitsSetArray256(arr(i) >> 24)
Next i
Return _count
End Function
On Dec 16, 2007 7:33 PM, Soormasher Singh <[EMAIL PROTECTED]> wrote:
> Hello All
>
> I'm trying to use Lucene.Net for faceting (Category counting and search
> refinement). I've not been able to find any examples of this using
> Lucene.Net. I've tried to use the approach used in Solr, but the performance
> hasn't been the greatest.
> Can anyone please help me with this? Any code/examples of anyone using
> Lucene.Net for category counting/faceting?
>
> Thanks a bunch!
>
>
>
>
>
>
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