longs = (np.random.rand(60, 1) + np.linspace(-np.pi, np.pi, 80000)).reshape(-1)
lats = np.sin(longs) + np.random.rand(len(longs)) * 0.1
bad_index = (longs > 0) & (longs < 1)
bad_longs = longs[bad_index]
bad_lats = lats[bad_index]
3g coverage map - visualise lat, long, ping data