set-intersection

Common elements in two lists with duplicates

由 懵懂的女人 提交于 2019-12-08 07:37:55
问题 I want to find the common elements in two [lists, vectors, sequences] when there can be duplicates. (common-elements [1] [1]) ; [1] (common-elements [1 2] [1 1]) ; [1] (common-elements [1 1] [1 1 1]) ; [1 1] Here is what I currently have: (defn remove-first [elem coll] (lazy-seq (when-let [s (seq coll)] (let [f (first s), r (rest s)] (if (= elem f) r (cons f (remove-first elem r))))))) (defn common-elements [coll1 coll2] (lazy-seq (when (and (seq coll1) (seq coll2)) (let [f (first coll1)] (if

Common elements in two lists with duplicates

由 假装没事ソ 提交于 2019-12-06 14:55:29
I want to find the common elements in two [lists, vectors, sequences] when there can be duplicates. (common-elements [1] [1]) ; [1] (common-elements [1 2] [1 1]) ; [1] (common-elements [1 1] [1 1 1]) ; [1 1] Here is what I currently have: (defn remove-first [elem coll] (lazy-seq (when-let [s (seq coll)] (let [f (first s), r (rest s)] (if (= elem f) r (cons f (remove-first elem r))))))) (defn common-elements [coll1 coll2] (lazy-seq (when (and (seq coll1) (seq coll2)) (let [f (first coll1)] (if (some #{f} coll2) (cons f (common-elements (rest coll1) (remove-first f coll2))) (common-elements

How to get an interesect query using CritieraQuery?

由 纵饮孤独 提交于 2019-12-06 12:47:39
问题 Given @Entity public class Document { @Id @Column(name = "DOCUMENT_ID") private Long id; @ElementCollection @CollectionTable( name="TAG", joinColumns=@JoinColumn(name="DOCUMENT_ID") ) @Column(name="TAG") private Set<String> tags; } find all documents tagged with a specific collection of tags. Essentially, an EclipseLink equivalent of: SELECT d FROM Document d WHERE :tag1 MEMBER OF d.tags INTERSECT SELECT d FROM Document d WHERE :tag2 MEMBER OF d.tags ... SELECT d FROM Document d WHERE :tagn

Set operations in Appengine datastore

由 二次信任 提交于 2019-12-06 00:21:51
I assume there's no good way to do so, but if you had to, how would you implement set operations on Appengine's datastore? For example given two collections of integers, how would you store them in the datastore to get a good performance for intersect and except (all those items in A that are not in B) operations? There aren't any built in set operations in the datastore API. I see you having two options: For smallish sets (hundreds of items) You might get away with doing keys-only queries for both set A and set B, and doing the intersection in your application code. The precise definition of

Trying to understand “except all” in sql query

由 房东的猫 提交于 2019-12-05 04:26:19
I came across this example and I don't understand what it means. (SELECT drinker FROM Frequents) EXCEPT ALL (SELECT drinker FROM Likes); relations: Frequents(drinker, bar), Likes(drinker, beer) What does the ALL do in this case? How is the result different from the query below? (SELECT drinker FROM Frequents) EXCEPT (SELECT drinker FROM Likes); The SQL EXCEPT operator takes the distinct rows of one query and returns the rows that do not appear in a second result set. The EXCEPT ALL operator does not remove duplicates. For purposes of row elimination and duplicate removal, the EXCEPT operator

Efficient set intersection of a collection of sets in C++

由 混江龙づ霸主 提交于 2019-12-04 19:17:46
问题 I have a collection of std::set . I want to find the intersection of all the sets in this collection, in the fastest manner. The number of sets in the collection is typically very small (~5-10), and the number of elements in each set is is usually less than 1000, but can occasionally go upto around 10000. But I need to do these intersections tens of thousands of time, as fast as possible. I tried to benchmark a few methods as follows: In-place intersection in a std::set object which initially

C++ - Finding intersection of two ranges

由 淺唱寂寞╮ 提交于 2019-12-04 18:00:13
问题 What is the best way to find the intersection of two ranges in C++? For example, if I have one range as [1...20] inclusive, and another as [13...45] inclusive, I want to get [13...20], as that is the intersection between them. I thought about using the native set intersection function in C++, but I would first have to convert the range into a set, which would take too much computation time for large values. 回答1: intersection = { std::max(arg1.min, arg2.min), std::min(arg1.max, arg2.max) }; if

What happens if I use vector::begin() instead of std::back_inserter(vector) for output of set_intersection?

由 主宰稳场 提交于 2019-12-04 03:03:11
问题 I have been using the highly concise and intuitive C++ syntax for finding the intersection of two sorted vector s and putting the result in a third vector : vector<bar> a,b,c; //... std::set_intersection(a.begin(),a.end(),b.begin(),b.end(), std::back_inserter(c)); This should set c to intersection( a , b ), assuming a and b are sorted. But what if I just use c.begin() (I thought I saw an example somewhere of this, which is why I did): std::set_intersection(a.begin(),a.end(),b.begin(),b.end(),

C++ - Finding intersection of two ranges

由 拈花ヽ惹草 提交于 2019-12-04 01:40:05
What is the best way to find the intersection of two ranges in C++? For example, if I have one range as [1...20] inclusive, and another as [13...45] inclusive, I want to get [13...20], as that is the intersection between them. I thought about using the native set intersection function in C++, but I would first have to convert the range into a set, which would take too much computation time for large values. intersection = { std::max(arg1.min, arg2.min), std::min(arg1.max, arg2.max) }; if (intersection.max < intersection.min) { intersection.markAsEmpty(); } yau For the sake of completeness I

Custom intersect in lambda

由 回眸只為那壹抹淺笑 提交于 2019-12-03 17:07:30
问题 I would like to know if this is possible to solve using a lambda expression: List<Foo> listOne = service.GetListOne(); List<Foo> listTwo = service.GetListTwo(); List<Foo> result = new List<Foo>(); foreach(var one in listOne) { foreach(var two in listTwo) { if((one.Id == two.Id) && one.someKey != two.someKey) result.Add(one); } } 回答1: Sure you can! You can use this overload of Linq's Intersect extension method which takes an IEqualityComparer<T> , like this: public class FooComparer :
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