Converting web mercator projections

conversions.py

scale_factor = np.pi/128.

inverse_scale_factor = 1/scale_factor

def lam(x, z):
    return np.rad2deg(x / np.power(2, zoom) * scale_factor - np.pi)

def phi(y, z):
    angle = np.pi - scale_factor * y/(np.power(2, z))
    
    return np.rad2deg(2 * np.arctan(np.exp(angle)) - np.pi/2)

def easting(lam, z):
    return inverse_scale_factor * np.power(2, z) * (lam + np.pi)

def northing(phi, z):
    angle = np.pi - np.log(np.tan(np.pi/4 + phi/2))
    return inverse_scale_factor * np.power(2, z) * angle

def convert2latlon(x, z):
    return np.array([
        lam(x[0], z),
        phi(x[1], z)
    ])

def convert2px(x, z):
    return np.array([
        easting(np.deg2rad(x[0]), z),
        northing(np.deg2rad(x[1]), z)
    ])