Harmonic Pattern Engine

import pandas as pd, numpy as np
from scipy.signal import argrelextrema

HARMONIC_RATIOS = {
    "gartley":    {"XB": (0.618, 0.618), "AC": (0.382, 0.886), "BD": (1.272, 1.618), "XD": (0.786, 0.786)},
    "butterfly":  {"XB": (0.786, 0.786), "AC": (0.382, 0.886), "BD": (1.618, 2.618), "XD": (1.272, 1.618)},
    "bat":        {"XB": (0.382, 0.500), "AC": (0.382, 0.886), "BD": (1.618, 2.618), "XD": (0.886, 0.886)},
    "crab":       {"XB": (0.382, 0.618), "AC": (0.382, 0.886), "BD": (2.240, 3.618), "XD": (1.618, 1.618)},
    "cypher":     {"XB": (0.382, 0.618), "AC": (1.130, 1.414), "BD": (1.272, 2.000), "XD": (0.786, 0.786)},
}

class HarmonicEngine: