python - Grouping Django Model Instances -

i've looked around , can't find this, i'm asking...

i have database 50 states , populations stored in integer field. none of populations same.

i create 10 groups of 5 states ordered population size, 5 populous states in group one, 5 next populous in group two, , on.

i'm creating data migration form these groups , save groupings , i'm not sure how iterate on instances.

size_of_group = 5 all_states = state.objects.order_by('-population') grouped_states = [all_states[i:i + size_of_group] in xrange(0, len(all_states), size_of_group)] 

it give list of sublists. each sublist contains size_of_group states. grouped_states[0] have 5 biggest populations. '-population' says order descending.

assuming model looks like:

class state(models.model)   population = models.integerfield()