def m_vector(self, m):
"""
Find David Lewin's M-vector.
(Also described in Composition with Pitch Classes - Robert Morris)
Finds the number of each set-class with cardinality m which are
subsets of a given pitch class. The ICV is equivalent to the m-vector
of a pitch class when m is 2.
"""
if m > self._mod:
return
from sator.pcset import PCSet
pc_set = self._pc_set
vectors = {}
for index, each in enumerate(self.__class__.each_card_in_mod(m, self._mod)):
e_prime = each.pcint
old_value = vectors.get(e_prime, 0)
to_add = 1 if pc_set.issuperset(each._pc_set) else 0
vectors[e_prime] = old_value + to_add
return sorted([(PCSet.fromint(pcint), total) \
for pcint, total in vectors.items()],
key = lambda x: x[0].pcint)
