def cosine_sim(known_point, new_point):
    from math import sqrt
    up, d1, d2 = 0.0, 0.0, 0.0
    a, b = known_point, new_point
    for key in a.wifi_snr:
        d1 += a.wifi_snr[key] * a.wifi_snr[key]
        if key in b.wifi_snr:
            up += a.wifi_snr[key] * b.wifi_snr[key]
    for key in b.wifi_snr:
        d2 += b.wifi_snr[key] * b.wifi_snr[key]
    if up == 0:
        return None
    else:
        return up / sqrt(d1) / sqrt(d2)

if __name__ == '__main__':
    from wifiloc import toplev
    toplev(infile = "basicdata.csv", sim = cosine_sim, bad_wifi_crit = 5000,
            sim_crit = 0.0)