stream.py 文件源码

def shift_waveform(tr, dtshift):
    """
    tr_shift = shift_waveform(tr, dtshift):

    Shift data in trace tr by dtshift seconds backwards.

    Parameters
    ----------
    tr : obspy.Trace
        Trace that contains the data to shift

    dtshift : float
        Time shift in seconds


    Returns
    -------
    tr_shift : obspy.Trace
        Copy of tr, but with data shifted dtshift seconds backwards.

    """
    data_pad = np.r_[tr.data, np.zeros_like(tr.data)]

    freq = fft.fftfreq(len(data_pad), tr.stats.delta)
    shiftvec = np.exp(- 2 * np.pi * complex(0., 1.) * freq * dtshift)
    data_fd = shiftvec * fft.fft(data_pad *
                                 signal.tukey(len(data_pad),
                                              alpha=0.2))

    tr.data = np.real(fft.ifft(data_fd))[0:tr.stats.npts]