calc_freq_from_midi

"""
This request comes from a forum.
He wanted to do a fft and plot instead the frequencies the notes.
BTW: I have no clue about music...
"""

from itertools import product


def calc_freq_from_midi(m, base_freq=440):
    if m < 0 or m > 127:
        raise ValueError('m must be between 0 and 127.')
    notes = ('C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B')
    octaves = range(-1, 10)
    notes = product(octaves, notes)
    notes = [note + str(band) for band, note in notes]
    freq = base_freq * 2 ** ((m - 69)/12)
    return freq, notes[m]

def printer(labels, even=False):
    for freq, note in labels:
        if not even or freq.is_integer():
            print(f'{freq:>10.2f} Hz: {note}')

labels440 = [calc_freq_from_midi(m) for m in range(128)]
labels432 = [calc_freq_from_midi(m, 432) for m in range(128)]

printer(labels440)
printer(labels432)