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simple_abc_parser.py
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simple_abc_parser.py
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# Copyright (C) 2011 Nils Liberg (mail: kotorinl at yahoo.co.uk)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from fractions import Fraction
key_data = \
{'c': ('#', 0), 'am': ('#', 0), 'ddor': ('#', 0),
'f': ('b', 1), 'dm': ('b', 1), 'gdor': ('#', 1),
'bb': ('b', 2), 'gm': ('b', 2), 'cdor': ('#', 2),
'eb': ('b', 3), 'cm': ('b', 3), 'bbdor': ('#', 3),
'ab': ('b', 4), 'fm': ('b', 4), 'ebdor': ('#', 4),
'db': ('b', 5), 'bbm': ('b', 5), 'abdor': ('#', 5),
'gb': ('b', 6), 'ebm': ('b', 6), 'abdor': ('#', 6),
'cb': ('b', 7), 'abm': ('b', 7), 'dbdor': ('#', 7),
'g': ('#', 1), 'em': ('#', 1), 'ador': ('#', 0),
'd': ('#', 2), 'bm': ('#', 2), 'edor': ('#', 0),
'a': ('#', 3), 'f#m': ('#', 3), 'bdor': ('#', 0),
'e': ('#', 4), 'c#m': ('#', 4), 'f#dor': ('#', 0),
'b': ('#', 5), 'g#m': ('#', 5), 'c#dor': ('#', 0),
'f#': ('#', 6), 'd#m': ('#', 6), 'g#dor': ('#', 0),
'c#': ('#', 7), 'a#m': ('#', 7), 'c#dor': ('#', 0),}
def get_base_note_for_key(key):
key = key[:2]
#print key, notes_sharp, notes_flat
if key in notes_sharp:
return notes_sharp.index(key)
if key in notes_flat:
return notes_flat.index(key)
key = key[:1]
if key in notes_sharp:
return notes_sharp.index(key)
if key in notes_flat:
return notes_flat.index(key)
raise Exception("error, incorrect key:%s" % key)
def get_best_key_for_midi_notes(notes):
notes = [n % 12 for n in notes]
penalty_key_tuples = []
for key in key_data:
accidentals = get_accidentals_for_key(key)
basic_notes_in_key = [x+y for x,y in zip(doremi2chromatic, accidentals)]
penalty = len([note for note in notes if not note in basic_notes_in_key])
if notes[-1] != get_base_note_for_key(key):
penalty += 2
if key.endswith('dor'):
penalty += 1
penalty_key_tuples.append((penalty, key))
penalty_key_tuples.sort()
#print '\n'.join((str(x) for x in penalty_key_tuples))
#print 'notes[-1]=', notes[-1]
#print 'penalty', penalty_key_tuples[0][0]
return penalty_key_tuples[0][1] # key of the first (and best) item
def update_extra_accidentals_for_note(basic_accidentals, extra_accidentals, note):
# merge the basic and extra accidentals and let the later have precedence over the former
accidentals = [b if b is not None else a for a, b in zip(basic_accidentals, extra_accidentals)]
basic_notes_in_key = [x+y for x,y in zip(doremi2chromatic, basic_accidentals)]
current_notes_in_key = [x+y for x,y in zip(doremi2chromatic, accidentals)]
change = None
#if not note in current_notes_in_key:
# if
return { None: '',
0: '=',
-1: '_',
1: '^'}[change]
# map from do-re-mi scale index to chromatic interval
doremi2chromatic = [0, 2, 4, 5, 7, 9, 11, 13]
# map from note name to note number in a C scale
note2number = 'cdefgab'
notes_sharp = 'c c# d d# e f f# g g# a a# b'.split()
notes_flat = 'c db d eb e f gb g ab a bb b'.split()
def get_accidentals(fifths):
# determine the accidentals for one octave
steps = 'C D E F G A B'.split()
one_octave = [0] * 7
if fifths > 0:
for i in range(fifths):
one_octave[(3 + i*4) % 7] = 1
else:
for i in range(fifths+1, 1):
one_octave[(6 + i*4) % 7] = -1
scale = []
for i in range(7):
scale.append(steps[i] + {-1: 'b', 0: '', 1:'#'}[one_octave[i]])
print(' '.join(scale))
# use the same for all octaves
accidentals = {}
for octave in range(1, 7):
for step in range(7):
note = '%s%s' % (steps[step], octave) # eg. G4
accidentals[note] = one_octave[step]
return accidentals
def get_accidentals_for_key(key):
''' returns a list of seven values corresponding to the notes in the C scale. 1 means #, -1 means b, and 0 means no change. '''
key = key.lower().strip().strip()
sharp_or_flat, number = key_data[key]
# initially no of the seven notes are flat or sharp (0=neutral)
accidentals = [0] * 7
# add accidentals
for i in range(number):
if sharp_or_flat == '#':
accidentals[(3 - 3*i) % 7] = 1
else:
accidentals[(6 + 3*i) % 7] = -1
return accidentals
class Note:
def __init__(self, note, duration, ties_to_next=False, broken_rythm=''):
self.note = note # number of semitones from centre note
self.duration = duration # duration expressed as a Fraction object
self.ties_to_next = ties_to_next # whether the abc representation of this note ended with '-' representing a tie to the next note
self.broken_rythm = broken_rythm # the ABC broken rythm symbol or an empty string
# (used when the duration of the next note is established)
def __repr__(self):
''' returns a string representation of this Note object '''
notes = ('c', 'c#', 'd', 'd#', 'e', 'f', 'f#', 'g', 'g#', 'a', 'a#', 'b')
n = notes[self.note % 12].upper()
octave = self.note / 12
if octave > 0:
if octave >= 1:
n = n.lower()
if octave > 1:
n = n + "'" * (octave - 1)
elif octave < 0:
if abs(octave) > 1:
n = n + "," * abs(octave)
return n #+ str(self.duration)
def __str__(self):
return repr(self)
#print get_best_key_for_midi_notes([0, 2, 4, 6, 6, 6, 7, 0])
#print get_base_note_for_key('c')