import numpy as np
from scipy.optimize import leastsq

def hfitoff(data, xdeg):
    """
    Harmonic fit with offset
    """
    start, end = min(xdeg), max(xdeg)
    guess_amplitude = 4 * np.std(data)
    guess_phase = 0
    guess_offset = np.mean(data)
    optimize_func = lambda x: x[0] * np.sin((xdeg + x[1]) * np.pi / 180) + x[2] - data
    fit_amplitude, fit_phase, fit_offset = leastsq(optimize_func, [guess_amplitude, guess_phase, guess_offset])[0]
    if fit_amplitude < 0:
        fit_amplitude = -fit_amplitude
        fit_phase = fit_phase + 180
    fit_xdeg = np.linspace(start, end, 100)
    fit_data = fit_amplitude * np.sin((fit_xdeg + fit_phase) * np.pi / 180) + fit_offset
    ph_crest = 90 - fit_phase
    ph_crest = ph_crest % 360
    return (fit_amplitude, fit_phase, fit_offset, ph_crest, fit_xdeg, fit_data)