python,django,orm,django-queryset,set-theory

The answer in the link you provided should be correct. Basically what you need to do is exclude set A from set B. setA = MyModel.objects.filter(…) # Query for items belonging in set A setB = MyModel.objects.filter(…) # Query for items belonging in set B # setA and setB are...

java,set,set-intersection,set-theory

What would be the best way to do this in Java? The first part you are describing is a powerset (as I edited your question to include last week). You would then get the intersection for each set of sets in the powerset. Because you are doing a powerset...

A terminal object in a category by definition is an object T with the property that for any object C in the category, there is exactly one arrow C -> T. In the category of sets, a singleton object, for example {1} has this property: For any set S there...

mapping,combinatorics,computation-theory,np-complete,set-theory

You could create a bipartite graph in the following manner: For each element in the set X create a node in the U disjoint set of the graph For each subset in the set S create a node in the V disjoint set of the graph If element of X...

javascript,arrays,union,intersection,set-theory

filter() can at least hide the loops for you: A = [1,2,3,4,5]; B = [1,2,3,6,7]; C = intersection(A, B); D = arrayDiff(A, C); E = arrayDiff(B, C); console.log(JSON.stringify(C)); console.log(JSON.stringify(D)); console.log(JSON.stringify(E)); function intersection(a, b) { return a.filter( function(el) { return b.indexOf(el) >= 0; } ); } function arrayDiff(a, b) { return...

algorithm,computer-science,combinatorics,set-theory

We already know the answer for these cases (as you wrote in your examples): n=2 n=3 n=4 For n=5: You can partition from 2: 1 2 - 3 4 5. This is like dividing the 5 member set into two sets, first one n=2, and second one n=3. We can...

select distinct least(x,y), greatest(x,y) from the_table; least() and greatest() put the values into an order so that 1,2 and 2,1 are returned as 1,2. The distinct then removes the duplicates...

Presumably you are using this third party module since Python doesn't have a built-in orderedset. A quick look through the source code on github shows that the issuperset function is implemented as def issuperset(self, other): return other <= self Taking a look at how the less than or equal operator...

javascript,math,underscore.js,set-theory

I don't think this would perform faster with real data, but you can do it like this function reverseCartesian(cp, arr) { return _.chain(cp) .map(_.partial(_.difference, _, arr)) .uniq(function(currentItem) { return currentItem.join("|"); }) .value(); } console.log(reverseCartesian(cp, [3, 4])); // [ [ 1, 'a' ], [ 1, 'b' ], [ 2, 'a' ],...