我试图理解Python中的优秀设计模式，我想不出一种方法可以将这个巨大的功能分解成更小的部分而不会使代码混乱，过于复杂或简单丑陋。
我不想通过发布整个文件来混淆我的问题，我的意思是这个函数本身已经很大了。但是这个类只有两个方法：parse_midi（）和generate_midi（file_name，file_length）。
音高，速度，增量，持续时间和间隔都是MarkovChain对象。 MarkovChain是一个带有方法的简单类：add_event（event），generate_markov_dictionary（）和get_next_event（previous_event）。 MarkovChain.src_events是从中生成马尔可夫链的事件列表。它是一阶Markov链的简单实现。
def parse_midi(self):
# on_notes dictionary holds note_on events until corresponding note_of event is encountered
on_notes = {}
time = 0
previous_pitch = -1
tempos = []
delta = 0
for message in self.track_in:
time += message.time
delta += message.time
# There are also MetaMessages in a midi file, such as comments, track names, etc.
# We just ignore them
if isinstance(message, mido.Message) and message.type in ["note_on", "note_off"]:
# some midi files use note_on events with 0 velocity instead of note_oof events
# so we check if velocity > 0
if message.velocity > 0 and message.type == "note_on":
on_notes[message.note] = time
self.pitches.add_event(message.note)
self.velocities.add_event(message.velocity)
self.deltas.add_event(delta)
delta = 0
if previous_pitch == -1:
self.intervals.add_event(0)
else:
self.intervals.add_event(message.note - previous_pitch)
else:
# KeyError means note_off came without a prior associated note_on event!"
# Just ignore them
with ignored(KeyError):
self.durations.add_event(time - on_notes[message.note])
del on_notes[message.note]
previous_pitch = message.note
# Tempo might be many tempo changes in a midi file, so we store them all to later calculate an average tempo
elif message.type == "set_tempo":
tempos.append(message.tempo)
elif message.type == "time_signature":
self.time_signature = self.TimeSignature(message.numerator, message.denominator,
message.clocks_per_click, message.notated_32nd_notes_per_beat)
# some tracks might be aempty in a midi file. For example they might contain comments as track name, and no note events
if len(self.pitches.src_events) == 0:
print("There are no note events in track {}!\n"
"The file has {} tracks. Please try another one.".format(self.selected_track, self.num_tracks))
exit(1)
# a midi file might not contain tempo information at all. if it does, we calculate the average
# else we just assign a default tempo of 120 bpm
try:
self.average_tempo = int(sum(tempos) / len(tempos))
except ZeroDivisionError:
self.average_tempo = mido.bpm2tempo(120)