Source code for pychord.quality

import copy
from collections import OrderedDict
from typing import Tuple, List

from .constants.qualities import DEFAULT_QUALITIES
from .utils import note_to_val, val_to_note

[docs]class Quality: """ Chord quality """ def __init__(self, name: str, components: Tuple[int, ...]): """ Constructor of chord quality :param name: name of quality :param components: components of quality """ self._quality: str = name self.components: Tuple[int, ...] = components def __unicode__(self): return self._quality def __str__(self): return self._quality def __eq__(self, other): if not isinstance(other, Quality): raise TypeError(f"Cannot compare Quality object with {type(other)} object") return self.components == other.components def __ne__(self, other): return not self.__eq__(other) @property def quality(self): """ Get name of quality """ return self._quality
[docs] def get_components(self, root='C', visible=False): """ Get components of chord quality :param str root: the root note of the chord :param bool visible: returns the name of notes if True :rtype: list[str|int] :return: components of chord quality """ root_val = note_to_val(root) components = [v + root_val for v in self.components] if visible: components = [val_to_note(c, scale=root) for c in components] return components
[docs] def append_on_chord(self, on_chord, root): """ Append on chord To create Am7/G q = Quality('m7') q.append_on_chord('G', root='A') :param str on_chord: bass note of the chord :param str root: root note of the chord """ root_val = note_to_val(root) on_chord_val = note_to_val(on_chord) - root_val components = list(self.components) for idx, val in enumerate(self.components): if val % 12 == on_chord_val: components.remove(val) break if on_chord_val > root_val: on_chord_val -= 12 if on_chord_val not in components: components = [on_chord_val] + [ v for v in components if v % 12 != on_chord_val % 12 ] self.components = tuple(components)
[docs]class QualityManager: """ Singleton class to manage the qualities """ def __new__(cls, *args, **kwargs): if not hasattr(cls, "_instance"): cls._instance = super(QualityManager, cls).__new__(cls) cls._instance.load_default_qualities() return cls._instance
[docs] def load_default_qualities(self): self._qualities = OrderedDict([ (q, Quality(q, c)) for q, c in DEFAULT_QUALITIES ])
[docs] def get_quality(self, name: str, inversion: int = 0) -> Quality: if name not in self._qualities: raise ValueError(f"Unknown quality: {name}") # Create a new instance not to affect any existing instances q = copy.deepcopy(self._qualities[name]) # apply requested inversion : for i in range(inversion): n = q.components[0] while n < q.components[-1]: n += 12 q.components = q.components[1:] + (n,) return q
[docs] def set_quality(self, name: str, components: Tuple[int, ...]): """ Set a Quality This method will not affect any existing Chord instances. :param name: name of quality :param components: components of quality """ self._qualities[name] = Quality(name, components)
[docs] def find_quality_from_components(self, components: List[int]): """ Find a quality from components :param components: components of quality """ for q in self._qualities.values(): if list(q.components) == components: return copy.deepcopy(q) return None