def named_interval_class_segment(self):
r'''Named interval class segment of scale.
Returns interval-class segment.
'''
dics = []
for left, right in \
sequencetools.iterate_sequence_nwise(self, wrapped=True):
dic = left - right
dics.append(dic)
dicg = pitchtools.IntervalClassSegment(
items=dics,
item_class=pitchtools.NamedInversionEquivalentIntervalClass,
)
return dicg
def _analyze_chord(expr):
from abjad.tools import tonalanalysistools
pitches = pitchtools.PitchSegment.from_selection(expr)
npcset = pitchtools.PitchClassSet(
pitches,
item_class=pitchtools.NamedPitchClass,
)
ordered_npcs = []
letters = ('c', 'e', 'g', 'b', 'd', 'f', 'a')
for letter in letters:
for npc in npcset:
if npc.diatonic_pitch_class_name == letter:
ordered_npcs.append(npc)
ordered_npcs = pitchtools.PitchClassSegment(
ordered_npcs, item_class=pitchtools.NamedPitchClass)
for x in range(len(ordered_npcs)):
ordered_npcs = ordered_npcs.rotate(1)
segment = \
pitchtools.IntervalClassSegment(
items=mathtools.difference_series(ordered_npcs),
item_class=pitchtools.NamedInversionEquivalentIntervalClass,
)
if segment.is_tertian:
break
else:
return None
root = ordered_npcs[0]
class_ = tonalanalysistools.RootlessChordClass
rootless_chord_class = class_.from_interval_class_segment(segment)
bass = min(pitches).named_pitch_class
inversion = ordered_npcs.index(bass)
return tonalanalysistools.RootedChordClass(
root,
rootless_chord_class.quality_string,
rootless_chord_class.extent,
inversion,
)