将一个(标签)列表与另一个列表匹配，并检测公共元素的存在 [英] Matching a list (of tags) with another and detecting presence of common elements

问题描述

我的要求是匹配标签.在示例中，该特定的HourConstraint检查分配给Hour(23)的TeacherHour.

My requirement is to match tags. In the example, this particular HourConstraint checks the TeacherHour assigned to Hour(23).

具体来说，它将检查TeacherHour.attributes["tags"]中的值["asst_ct","teacher_john_smith"]和至少检测到一个匹配，在这种情况下为两个("asst_ct"和"teacher_john_smith").

Specifically, it checks TeacherHour.attributes["tags"] for the values ["asst_ct","teacher_john_smith"] and detects atleast one match, two in this case (both "asst_ct" and "teacher_john_smith") .

TeacherHour:
  id: 47
  assigned_hour: Null
  attributes:Map<List<String>>
    "tags":["asst_ct","no_strenuous_duties","kinda_boring","teacher_john_smith"]
    "another_attribute":[...]

HourConstraint:
   hour: Hour(23)
   attribute: "tags"
   values_list: ["asst_ct","teacher_john_smith"]

---

问题:如何检测两个列表之间是否存在(常见元素)?

---

Question: How do I detect the presence (true or false) of common elements between two lists?

Drools Expert具有memberOf和contains，但是它们检查标量与集合，而不是集合与集合.

Drools Expert has memberOf and contains, but they check a scalar vs a collection, never a collection vs a collection.

我看到了两种可能的方式:

I see two potential ways:

1. 引入一个函数boolean isIntersecting(list,list)并告​​诉Drools使用该函数进行真理检查
2. 将TeacherHour.attributes[]作为字符串而不是列表，并将HourConstraint.valueslist作为可与该列表匹配的正则表达式

1. introduce a function boolean isIntersecting(list,list) and tell Drools to use that for truth checking
2. Implement TeacherHour.attributes[] as a string instead of a list and HourConstraint.valueslist as a regular expression that can match that list

推荐答案

有一些选择.最直接的方法是使用Collections类为您做到这一点:

There are a few options. Most straight forward is to use the Collections class to do that for you:

rule X
when
    $t: TeacherHour( )
    HourConstraint( Collections.disjoint( $t.attributes["tags"], values_list ) == false )
...

如果这是您经常在规则中使用的东西，那么我建议将该函数包装在Drools支持的可插入运算符中.假设您将运算符命名为"intersect"，然后可以这样编写规则:

If this is something you would use often in your rules, then I recommend wrapping that function in a pluggable operator, supported by Drools. Lets say you name the operator "intersect", you can then write your rules like this:

rule X
when
    $t: TeacherHour( )
    HourConstraint( values_list intersect $t.attributes["tags"] )
...

第三个选项是使用"from"，但是在运行时效率较低，因为它会导致第一个列表上的迭代:

A third option, is to use "from", but that is less efficient in runtime as it causes iterations on the first list:

rule X
when
    $t: TeacherHour( )
    $tag : String() from $t.attributes["tags"]
    exists( HourConstraint( values_list contains $tag ) )
...

这篇关于将一个(标签)列表与另一个列表匹配，并检测公共元素的存在的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！