Generating all possible subsets of a given QuerySet in Django
- by Glen
This is just an example, but given the following model:
class Foo(models.model):
bar = models.IntegerField()
def __str__(self):
return str(self.bar)
def __unicode__(self):
return str(self.bar)
And the following QuerySet object:
foobar = Foo.objects.filter(bar__lt=20).distinct()
(meaning, a set of unique Foo models with bar <= 20), how can I generate all possible subsets of foobar? Ideally, I'd like to further limit the subsets so that, for each subset x of foobar, the sum of all f.bar in x (where f is a model of type Foo) is between some maximum and minimum value.
So, for example, given the following instance of foobar:
>> print foobar
[<Foo: 5>, <Foo: 10>, <Foo: 15>]
And min=5, max=25, I'd like to build an object (preferably a QuerySet, but possibly a list) that looks like this:
[[<Foo: 5>], [<Foo: 10>], [<Foo: 15>], [<Foo: 5>, <Foo: 10>],
[<Foo: 5>, <Foo: 15>], [<Foo: 10>, <Foo: 15>]]
I've experimented with itertools but it doesn't seem particularly well-suited to my needs.
I think this could be accomplished with a complex QuerySet but I'm not sure how to start.
