utils.py 文件源码

def peak_freq(signal,timebase,minfreq=0,maxfreq=1.e18):
    """
    TODO: old code: needs review
    this function only has a basic unittest to make sure it returns
    the correct freq in a simple case.
    """
    timebase = array(timebase)
    sig_fft = fft.fft(signal)
    sample_time = float(mean(timebase[1:]-timebase[:-1]))

    #SRH modification, frequencies seemed a little bit off because of the -1 in the denominator
    #Here we are trusting numpy....
    #fft_freqs = (1./sample_time)*arange(len(sig_fft)).astype(float)/(len(sig_fft)-1)
    fft_freqs = fft.fftfreq(len(sig_fft),d=sample_time)
    # only show up to nyquist freq
    new_len = len(sig_fft)/2
    sig_fft = sig_fft[:new_len]
    fft_freqs = fft_freqs[:new_len]
    [minfreq_elmt,maxfreq_elmt] = searchsorted(fft_freqs,[minfreq,maxfreq])
    sig_fft = sig_fft[minfreq_elmt:maxfreq_elmt]
    fft_freqs = fft_freqs[minfreq_elmt:maxfreq_elmt]

    peak_elmt = (argsort(abs(sig_fft)))[-1]
    return [fft_freqs[peak_elmt], peak_elmt]