[英]Counting string occurrences with ArangoDB AQL
要计算包含特定属性值的对象数量,我可以执行以下操作:
FOR t IN thing
COLLECT other = t.name = "Other" WITH COUNT INTO otherCount
FILTER other != false
RETURN otherCount
但是,如何在同一查询中计算其他三个出现次数,而不会导致子查询多次通过同一数据集运行?
我试过这样的事情:
FOR t IN thing
COLLECT
other = t.name = "Other",
some = t.name = "Some",
thing = t.name = "Thing"
WITH COUNT INTO count
RETURN {
other, some, thing,
count
}
但我无法理解结果:我一定以错误的方式接近这个?
拆分和计数
您可以按短语拆分字符串并从计数中减去 1。 这适用于任何子字符串,另一方面意味着它不考虑单词边界。
LET things = [
{name: "Here are SomeSome and Some Other Things, brOther!"},
{name: "There are no such substrings in here."},
{name: "some-Other-here-though!"}
]
FOR t IN things
LET Some = LENGTH(SPLIT(t.name, "Some"))-1
LET Other = LENGTH(SPLIT(t.name, "Other"))-1
LET Thing = LENGTH(SPLIT(t.name, "Thing"))-1
RETURN {
Some, Other, Thing
}
结果:
[
{
"Some": 3,
"Other": 2,
"Thing": 1
},
{
"Some": 0,
"Other": 0,
"Thing": 0
},
{
"Some": 0,
"Other": 1,
"Thing": 0
}
]
您可以使用SPLIT(LOWER(t.name), LOWER("..."))
使其不区分大小写。
收集单词
TOKENS()
函数可用于将输入拆分为单词数组,然后可以对其进行分组和计数。 请注意,我稍微更改了输入。 输入"SomeSome"
不会被计算在内,因为"somesome" != "some"
(这个变体是单词而不是基于子字符串的)。
LET things = [
{name: "Here are SOME some and Some Other Things. More Other!"},
{name: "There are no such substrings in here."},
{name: "some-Other-here-though!"}
]
LET whitelist = TOKENS("Some Other Things", "text_en")
FOR t IN things
LET whitelisted = (FOR w IN TOKENS(t.name, "text_en") FILTER w IN whitelist RETURN w)
LET counts = MERGE(FOR w IN whitelisted
COLLECT word = w WITH COUNT INTO count
RETURN { [word]: count }
)
RETURN {
name: t.name,
some: counts.some || 0,
other: counts.other || 0,
things: counts.things ||0
}
结果:
[
{
"name": "Here are SOME some and Some Other Things. More Other!",
"some": 3,
"other": 2,
"things": 0
},
{
"name": "There are no such substrings in here.",
"some": 0,
"other": 0,
"things": 0
},
{
"name": "some-Other-here-though!",
"some": 1,
"other": 1,
"things": 0
}
]
这确实使用了 COLLECT 的子查询,否则它将计算整个输入的总出现次数。
白名单步骤不是绝对必要的,您也可以让它计算所有单词。 对于较大的输入字符串,它可能会节省一些内存,以免对您不感兴趣的单词执行此操作。
如果您想精确匹配单词,您可能需要创建一个单独的分析器,并为语言禁用词干。 您还可以关闭规范化( "accent": true, "case": "none"
)。 另一种方法是对典型的空格和标点符号使用REGEX_SPLIT()
以进行更简单的标记化,但这取决于您的用例。
其他解决方案
我认为不可能在没有子查询的情况下使用 COLLECT 独立计算每个输入对象,除非您想要总数。
拆分有点麻烦,但您可以将 SPLIT() 替换为 REGEX_SPLIT() 并将搜索短语包装在\\b
以仅在单词边界在两侧时才匹配。 那么它应该只匹配单词(或多或少):
LET things = [
{name: "Here are SomeSome and Some Other Things, brOther!"},
{name: "There are no such substrings in here."},
{name: "some-Other-here-though!"}
]
FOR t IN things
LET Some = LENGTH(REGEX_SPLIT(t.name, "\\bSome\\b"))-1
LET Other = LENGTH(REGEX_SPLIT(t.name, "\\bOther\\b"))-1
LET Thing = LENGTH(REGEX_SPLIT(t.name, "\\bThings\\b"))-1
RETURN {
Some, Other, Thing
}
结果:
[
{
"Some": 1,
"Other": 1,
"Thing": 1
},
{
"Some": 0,
"Other": 0,
"Thing": 0
},
{
"Some": 0,
"Other": 1,
"Thing": 0
}
]
一个更优雅的解决方案是使用 ArangoSearch 进行单词计数,但它没有让您检索单词出现频率的功能。 它可能会在内部跟踪它(分析器功能“频率” ),但此时它绝对没有公开。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.