fingerprint.py 文件源码

def get_2D_peaks(arr2D, plot=False, amp_min=DEFAULT_AMP_MIN):
    # http://docs.scipy.org/doc/scipy/reference/generated/scipy.ndimage.morphology.iterate_structure.html#scipy.ndimage.morphology.iterate_structure
    struct = generate_binary_structure(2, 1)
    neighborhood = iterate_structure(struct, PEAK_NEIGHBORHOOD_SIZE)

    # find local maxima using our fliter shape
    local_max = maximum_filter(arr2D, footprint=neighborhood) == arr2D
    background = (arr2D == 0)
    eroded_background = binary_erosion(background, structure=neighborhood,
                                       border_value=1)

    # Boolean mask of arr2D with True at peaks
    detected_peaks = local_max - eroded_background

    # extract peaks
    amps = arr2D[detected_peaks]
    j, i = np.where(detected_peaks)

    # filter peaks
    amps = amps.flatten()
    peaks = zip(i, j, amps)
    peaks_filtered = [x for x in peaks if x[2] > amp_min]  # freq, time, amp

    # get indices for frequency and time
    frequency_idx = [x[1] for x in peaks_filtered]
    time_idx = [x[0] for x in peaks_filtered]

    # scatter of the peaks
    if plot:
      fig, ax = plt.subplots()
      ax.imshow(arr2D)
      ax.scatter(time_idx, frequency_idx)
      ax.set_xlabel('Time')
      ax.set_ylabel('Frequency')
      ax.set_title("Spectrogram")
      plt.gca().invert_yaxis()
      plt.show()

    return zip(frequency_idx, time_idx)

# Hash list structure: sha1_hash[0:20] time_offset
# example: [(e05b341a9b77a51fd26, 32), ... ]