Antijoins with Groovy Collections

Question

This is probably a silly question however, is there a simple way of doing antijoins of collections in Groovy?

I know there are [equivilent ways of doing unions and intersections].

My thought on how to do this is:

List a,b; 
union(a,b) - intersection(a,b)

However, I'm not sure if there is a difference operator for collections in groovy.

score 4 · Accepted Answer · answered Sep 13 '11 at 20:28

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It turns out that can you can do a subtraction operation on 2 lists, and receive a list back of the disjoint collection. Just use the subtraction operator between two lists.

 listone - listtwo

answered Sep 13 '11 at 20:28

monksy

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Watch out if you have duplicates in the lists though – tim_yates Sep 13 '11 at 20:44
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It depends on what [you require as the output](http://stackoverflow.com/questions/7386978/groovy-difference-with-a-intersect-b-and-b-intersect-a) – tim_yates Sep 14 '11 at 08:45

score 1 · Answer 2 · answered Sep 13 '11 at 20:08

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Afaik, there isn't an operator our method to do this for you (might be a cool addition to groovy though)

The closest I can think of is the disjoint method which returns true if there is no intersection between lists, and false otherwise

answered Sep 13 '11 at 20:08

tim_yates

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Antijoins with Groovy Collections

2 Answers2