samples/LuceneInAction/lia/extsearch/sorting/DistanceComparatorSource.py

   1 # ====================================================================
   2 #   Licensed under the Apache License, Version 2.0 (the "License");
   3 #   you may not use this file except in compliance with the License.
   4 #   You may obtain a copy of the License at
   5 #
   6 #       http://www.apache.org/licenses/LICENSE-2.0
   7 #
   8 #   Unless required by applicable law or agreed to in writing, software
   9 #   distributed under the License is distributed on an "AS IS" BASIS,
  10 #   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  11 #   See the License for the specific language governing permissions and
  12 #   limitations under the License.
  13 # ====================================================================
  14
  15 from math import sqrt
  16 from lucene import SortField, Term, IndexReader, FieldCache, \
  17     PythonFieldComparatorSource, PythonFieldComparator, Double
  18
  19 #
  20 # A FieldComparatorSource implementation
  21 #
  22
  23 class DistanceComparatorSource(PythonFieldComparatorSource):
  24
  25     def __init__(self, x, y):
  26         super(DistanceComparatorSource, self).__init__()
  27
  28         self.x = x
  29         self.y = y
  30
  31     def newComparator(self, fieldName, numHits, sortPos, reversed):
  32
  33         class DistanceScoreDocLookupComparator(PythonFieldComparator):
  34
  35             def __init__(_self, fieldName, numHits):
  36                 super(DistanceScoreDocLookupComparator, _self).__init__()
  37                 _self.values = [0.0] * numHits
  38                 _self.fieldName = fieldName
  39
  40             def setNextReader(_self, reader, docBase):
  41
  42                 _self.xDoc = FieldCache.DEFAULT.getInts(reader, "x")
  43                 _self.yDoc = FieldCache.DEFAULT.getInts(reader, "y")
  44
  45             def _getDistance(_self, doc):
  46
  47                 deltax = _self.xDoc[doc] - self.x
  48                 deltay = _self.yDoc[doc] - self.y
  49
  50                 return sqrt(deltax * deltax + deltay * deltay)
  51
  52             def compare(_self, slot1, slot2):
  53
  54                 if _self.values[slot1] < _self.values[slot2]:
  55                     return -1
  56                 if _self.values[slot1] > _self.values[slot2]:
  57                     return 1
  58
  59                 return 0
  60
  61             def setBottom(_self, slot):
  62
  63                 _self._bottom = _self.values[slot]
  64
  65             def compareBottom(_self, doc):
  66
  67                 docDistance = _self._getDistance(doc)
  68                 if _self._bottom < docDistance:
  69                     return -1
  70                 if _self._bottom > docDistance:
  71                      return 1
  72
  73                 return 0
  74
  75             def copy(_self, slot, doc):
  76
  77                 _self.values[slot] = _self._getDistance(doc)
  78
  79             def value(_self, slot):
  80
  81                 return Double(_self.values[slot])
  82
  83             def sortType(_self):
  84                 return SortField.CUSTOM
  85
  86         return DistanceScoreDocLookupComparator(fieldName, numHits)
  87
  88     def __str__(self):
  89
  90         return "Distance from (" + self.x + "," + self.y + ")"