我在lucene中测试boost运算符,发现奇怪的行为
例
query1 = "red fox"
query2 = "red^1.2 fox"
当我针对文本测试查询时:
“很棒的红狐狸”
我获得了query2的得分低于query1的得分。但是我希望query2应该赢。
以下查询说明
解释查询1
{0,4339554 = (MATCH) sum of:
0,2169777 = (MATCH) weight(content:fox in 0), product of:
0,7071068 = queryWeight(content:fox), product of:
0,3068528 = idf(docFreq=1, maxDocs=1)
2,304384 = queryNorm
0,3068528 = (MATCH) fieldWeight(content:fox in 0), product of:
1 = tf(termFreq(content:fox)=1)
0,3068528 = idf(docFreq=1, maxDocs=1)
1 = fieldNorm(field=content, doc=0)
0,2169777 = (MATCH) weight(content:red in 0), product of:
0,7071068 = queryWeight(content:red), product of:
0,3068528 = idf(docFreq=1, maxDocs=1)
2,304384 = queryNorm
0,3068528 = (MATCH) fieldWeight(content:red in 0), product of:
1 = tf(termFreq(content:red)=1)
0,3068528 = idf(docFreq=1, maxDocs=1)
1 = fieldNorm(field=content, doc=0)
}
解释查询2
{0,4313012 = (MATCH) sum of:
0,2396118 = (MATCH) weight(content:fox^1.25 in 0), product of:
0,7808688 = queryWeight(content:fox^1.25), product of:
1,25 = boost
0,3068528 = idf(docFreq=1, maxDocs=1)
2,035813 = queryNorm
0,3068528 = (MATCH) fieldWeight(content:fox in 0), product of:
1 = tf(termFreq(content:fox)=1)
0,3068528 = idf(docFreq=1, maxDocs=1)
1 = fieldNorm(field=content, doc=0)
0,1916894 = (MATCH) weight(content:red in 0), product of:
0,6246951 = queryWeight(content:red), product of:
0,3068528 = idf(docFreq=1, maxDocs=1)
2,035813 = queryNorm
0,3068528 = (MATCH) fieldWeight(content:red in 0), product of:
1 = tf(termFreq(content:red)=1)
0,3068528 = idf(docFreq=1, maxDocs=1)
1 = fieldNorm(field=content, doc=0)
}
我不知道为什么提升查询的得分比普通查询低?
最佳答案
这是由于查询规范。计分算法的此功能试图使分数从一个查询到下一个查询大致可比。
计算公式为:
queryNorm = 1 /sumOfSquaredWeights½
哪里:
sumOfSquaredWeights =查询boost2·∑(idf·词条boost)2
如果从解释中删除该因素,只需将最终分数除以查询范数,您就会发现第二个查询确实确实获得了更高的分数:
query1-> .4339554 / 2.304384 = 0.1883
query2-> .4313012 / 2.035813 = 0.2119
不过,更大的一点是:在比较一个查询与下一个查询的分数时,您不应读太多。分数仅与生成分数的查询真正相关。您可以在解释中看到,提升词对得分的相对权重更大,这实际上是所有提升的目的。
关于c# - 为什么lucene增强查询的得分低于相同的普通查询?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/40250210/