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Reformat with black
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@davidparsson
davidparsson committed May 1, 2024
1 parent 2076163 commit 696cd57
Showing 1 changed file with 160 additions and 133 deletions.
293 changes: 160 additions & 133 deletions transposer.py
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import os
import re, getopt

key_list = [('A',), ('A#', 'Bb'), ('B',), ('C',), ('C#', 'Db'), ('D',),
('D#', 'Eb'), ('E',), ('F',), ('F#', 'Gb'), ('G',), ('G#', 'Ab')]

sharp_flat = ['#', 'b']
key_list = [
("A",),
("A#", "Bb"),
("B",),
("C",),
("C#", "Db"),
("D",),
("D#", "Eb"),
("E",),
("F",),
("F#", "Gb"),
("G",),
("G#", "Ab"),
]

sharp_flat = ["#", "b"]
sharp_flat_preferences = {
'A' : '#',
'A#': 'b',
'Bb': 'b',
'B' : '#',
'C' : 'b',
'C#': 'b',
'Db': 'b',
'D' : '#',
'D#': 'b',
'Eb': 'b',
'E' : '#',
'F' : 'b',
'F#': '#',
'Gb': '#',
'G' : '#',
'G#': 'b',
'Ab': 'b',
}
"A": "#",
"A#": "b",
"Bb": "b",
"B": "#",
"C": "b",
"C#": "b",
"Db": "b",
"D": "#",
"D#": "b",
"Eb": "b",
"E": "#",
"F": "b",
"F#": "#",
"Gb": "#",
"G": "#",
"G#": "b",
"Ab": "b",
}

key_regex = re.compile(r"[ABCDEFG][#b]?")


def get_index_from_key(source_key):
"""Gets the internal index of a key
>>> get_index_from_key('Bb')
1
"""
for key_names in key_list:
if source_key in key_names:
return key_list.index(key_names)
raise Exception("Invalid key: %s" % source_key)
"""Gets the internal index of a key
>>> get_index_from_key('Bb')
1
"""
for key_names in key_list:
if source_key in key_names:
return key_list.index(key_names)
raise Exception("Invalid key: %s" % source_key)


def get_key_from_index(index, to_key):
"""Gets the key at the given internal index.
Sharp or flat depends on the target key.
>>> get_key_from_index(1, 'Eb')
'Bb'
"""
key_names = key_list[index % len(key_list)]
if len(key_names) > 1:
sharp_or_flat = sharp_flat.index(sharp_flat_preferences[to_key])
return key_names[sharp_or_flat]
return key_names[0]
"""Gets the key at the given internal index.
Sharp or flat depends on the target key.
>>> get_key_from_index(1, 'Eb')
'Bb'
"""
key_names = key_list[index % len(key_list)]
if len(key_names) > 1:
sharp_or_flat = sharp_flat.index(sharp_flat_preferences[to_key])
return key_names[sharp_or_flat]
return key_names[0]


def get_transponation_steps(source_key, target_key):
"""Gets the number of half tones to transpose
>>> get_transponation_steps('D', 'C')
-2
"""
source_index = get_index_from_key(source_key)
target_index = get_index_from_key(target_key)
return target_index - source_index
"""Gets the number of half tones to transpose
>>> get_transponation_steps('D', 'C')
-2
"""
source_index = get_index_from_key(source_key)
target_index = get_index_from_key(target_key)
return target_index - source_index


def transpose_file(file_name, from_key, to_key):
"""Transposes a file from a key to another.
>>> transpose_file('example.txt', 'D', 'E')
'Rocking start, jazzy ending\\n| E | A B | Cm7#11/D# |\\n'
"""
direction = get_transponation_steps(from_key, to_key)
result = ''
try:
for line in open(file_name):
result += transpose_line(line, direction, to_key)
return result
except IOError:
print("Invalid filename!")
usage()
"""Transposes a file from a key to another.
>>> transpose_file('example.txt', 'D', 'E')
'Rocking start, jazzy ending\\n| E | A B | Cm7#11/D# |\\n'
"""
direction = get_transponation_steps(from_key, to_key)
result = ""
try:
for line in open(file_name):
result += transpose_line(line, direction, to_key)
return result
except IOError:
print("Invalid filename!")
usage()


def transpose_line(source_line, direction, to_key):
"""Transposes a line a number of keys if it starts with a pipe. Examples:
>>> transpose_line('| A | A# | Bb | C#m7/F# |', -2, 'C')
'| G | Ab | Ab | Bm7/E |'
Different keys will be sharp or flat depending on target key.
>>> transpose_line('| A | A# | Bb | C#m7/F# |', -2, 'D')
'| G | G# | G# | Bm7/E |'
It will use the more common key if sharp/flat, for example F# instead of Gb.
>>> transpose_line('| Gb |', 0, 'Gb')
'| F# |'
Lines not starting with pipe will not be transposed
>>> transpose_line('A | Bb |', -2, 'C')
'A | Bb |'
"""
if source_line[0] != '|':
return source_line
source_chords = key_regex.findall(source_line)
return recursive_line_transpose(source_line, source_chords, direction, to_key)

"""Transposes a line a number of keys if it starts with a pipe. Examples:
>>> transpose_line('| A | A# | Bb | C#m7/F# |', -2, 'C')
'| G | Ab | Ab | Bm7/E |'
Different keys will be sharp or flat depending on target key.
>>> transpose_line('| A | A# | Bb | C#m7/F# |', -2, 'D')
'| G | G# | G# | Bm7/E |'
It will use the more common key if sharp/flat, for example F# instead of Gb.
>>> transpose_line('| Gb |', 0, 'Gb')
'| F# |'
Lines not starting with pipe will not be transposed
>>> transpose_line('A | Bb |', -2, 'C')
'A | Bb |'
"""
if source_line[0] != "|":
return source_line
source_chords = key_regex.findall(source_line)
return recursive_line_transpose(source_line, source_chords, direction, to_key)


def recursive_line_transpose(source_line, source_chords, direction, to_key):
if not source_chords or not source_line:
return source_line
source_chord = source_chords.pop(0)
chord_index = source_line.find(source_chord)
after_chord_index = chord_index + len(source_chord)

return source_line[:chord_index] + \
transpose(source_chord, direction, to_key) + \
recursive_line_transpose(source_line[after_chord_index:], source_chords, direction, to_key)
if not source_chords or not source_line:
return source_line
source_chord = source_chords.pop(0)
chord_index = source_line.find(source_chord)
after_chord_index = chord_index + len(source_chord)

return (
source_line[:chord_index]
+ transpose(source_chord, direction, to_key)
+ recursive_line_transpose(
source_line[after_chord_index:], source_chords, direction, to_key
)
)


def transpose(source_chord, direction, to_key):
"""Transposes a chord a number of half tones.
Sharp or flat depends on target key.
>>> transpose('C', 3, 'Bb')
'Eb'
"""
source_index = get_index_from_key(source_chord)
return get_key_from_index(source_index + direction, to_key)
"""Transposes a chord a number of half tones.
Sharp or flat depends on target key.
>>> transpose('C', 3, 'Bb')
'Eb'
"""
source_index = get_index_from_key(source_chord)
return get_key_from_index(source_index + direction, to_key)


def usage():
print('Usage:')
print('%s --from=Eb --to=F# input_filename' % os.path.basename(__file__))
sys.exit(2)
print("Usage:")
print("%s --from=Eb --to=F# input_filename" % os.path.basename(__file__))
sys.exit(2)


def main():
from_key = 'C'
to_key = 'C'
file_name = None
try:
options, arguments = getopt.getopt(sys.argv[1:], 'f:t:', ['from=', 'to=', 'doctest'])
except getopt.GetoptError as err:
print(str(err))
usage()
sys.exit(2)
for option, value in options:
if option in ('-f', '--from'):
from_key = value
elif option in ('-t', '--to'):
to_key = value
elif option == '--doctest':
import doctest
doctest.testmod()
exit()
else:
usage()

if arguments:
file_name = arguments[0]
else:
usage()

result = transpose_file(file_name, from_key, to_key)

print("Result (%s -> %s):" % (from_key, to_key))
print(result)

if __name__ == '__main__':
main()
from_key = "C"
to_key = "C"
file_name = None
try:
options, arguments = getopt.getopt(
sys.argv[1:], "f:t:", ["from=", "to=", "doctest"]
)
except getopt.GetoptError as err:
print(str(err))
usage()
sys.exit(2)
for option, value in options:
if option in ("-f", "--from"):
from_key = value
elif option in ("-t", "--to"):
to_key = value
elif option == "--doctest":
import doctest

doctest.testmod()
exit()
else:
usage()

if arguments:
file_name = arguments[0]
else:
usage()

result = transpose_file(file_name, from_key, to_key)

print("Result (%s -> %s):" % (from_key, to_key))
print(result)


if __name__ == "__main__":
main()

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