'Sets the location of theta\'s zero.  (Calls set_theta_offset
with the correct value in radians under the hood.)
May be one of "N", "NW", "W", "SW", "S", "SE", "E", or "NE".'

def set_theta_zero_location(self, loc):

    mapping = {u'N': (np.pi * 0.5), u'NW': (np.pi * 0.75), u'W': np.pi, u'SW': (np.pi * 1.25), u'S': (np.pi * 1.5), u'SE': (np.pi * 1.75), u'E': 0, u'NE': (np.pi * 0.25)}
    return self.set_theta_offset(mapping[loc])
