plots.py 文件源码

def plotfilt(b, fs:int, ofn=None):
    if fs is None:
        fs=1 #normalized freq

    L = b.size

    fg,axs = subplots(2,1,sharex=False)
    freq, response = signal.freqz(b)
    response_dB = 20*np.log10(abs(response))
    if response_dB.max()>0:
        logging.error('filter may be unstable')

    axs[0].plot(freq*fs/(2*np.pi), response_dB)
    axs[0].set_title(f'filter response  {L} taps')
    axs[0].set_ylim((-100,None))
    axs[0].set_ylabel('|H| [db]')
    axs[0].set_xlabel('frequency [Hz]')

    t = np.arange(0, L/fs, 1/fs)
    axs[1].plot(t,b)
    axs[1].set_xlabel ('time [sec]')
    axs[1].set_title('impulse response')
    axs[1].set_ylabel('amplitude')
    axs[1].autoscale(True,tight=True)

    fg.tight_layout()

    if ofn:
        ofn = Path(ofn).expanduser()
        ofn = ofn.with_suffix('.png')
        print('writing',ofn)
        fg.savefig(str(ofn),dpi=100,bbox_inches='tight')