Coverage for local/lib/python2.7/site-packages/sage/combinat/integer_lists/nn.py : 100%

from __future__ import print_function 

from sage.sets.family import Family 

from sage.combinat.integer_lists import IntegerListsLex 

from sage.rings.semirings.non_negative_integer_semiring import NN 

from sage.sets.disjoint_union_enumerated_sets import DisjointUnionEnumeratedSets 

def IntegerListsNN(**kwds): 

""" 

Lists of nonnegative integers with constraints. 

This function returns the union of ``IntegerListsLex(n, **kwds)`` 

where `n` ranges over all nonnegative integers. 

EXAMPLES:: 

sage: from sage.combinat.integer_lists.nn import IntegerListsNN 

sage: L = IntegerListsNN(max_length=3, max_slope=-1) 

sage: L 

Disjoint union of Lazy family (<lambda>(i))_{i in Non negative integer semiring} 

sage: it = iter(L) 

sage: for _ in range(20): 

....: print(next(it)) 

[] 

[1] 

[2] 

[3] 

[2, 1] 

[4] 

[3, 1] 

[5] 

[4, 1] 

[3, 2] 

[6] 

[5, 1] 

[4, 2] 

[3, 2, 1] 

[7] 

[6, 1] 

[5, 2] 

[4, 3] 

[4, 2, 1] 

[8] 

""" 

return DisjointUnionEnumeratedSets(Family(NN, lambda i: IntegerListsLex(i, **kwds)))