Source code for eqcorrscan.utils.findpeaks

r"""Functions to find peaks in data above a certain threshold.

:copyright:
    EQcorrscan developers.

:license:
    GNU Lesser General Public License, Version 3
    (https://www.gnu.org/copyleft/lesser.html)
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

import random
import numpy as np

from obspy import UTCDateTime
from scipy import ndimage


def is_prime(number):
    """
    Function to test primality of a number. Function lifted from online
    resource:
        http://www.codeproject.com/Articles/691200/Primality-test-algorithms-Prime-test-The-fastest-w

    This function is distributed under a separate licence:
        This article, along with any associated source code and files, is \
        licensed under The Code Project Open License (CPOL)

    :type number: int
    :param number: Integer to test for primality

    :returns: bool

    >>> is_prime(4)
    False
    >>> is_prime(3)
    True
    """
    ''' if number != 1 '''
    if number > 1:
        ''' repeat the test few times '''
        for time in range(3):
            ''' Draw a RANDOM number in range of number ( Z_number )  '''
            randomNumber = random.randint(2, number - 1)
            ''' Test if a^(n-1) = 1 mod n '''
            if pow(randomNumber, number - 1, number) != 1:
                return False
        return True
    else:
        ''' case number == 1 '''
        return False


[docs]def find_peaks2_short(arr, thresh, trig_int, debug=0, starttime=False, samp_rate=1.0): """ Determine peaks in an array of data above a certain threshold. Uses a mask to remove data below threshold and finds peaks in what is left. :type arr: numpy.ndarray :param arr: 1-D numpy array is required :type thresh: float :param thresh: The threshold below which will be considered noise and \ peaks will not be found in. :type trig_int: int :param trig_int: The minimum difference in samples between triggers,\ if multiple peaks within this window this code will find the highest. :type debug: int :param debug: Optional, debug level 0-5 :type starttime: obspy.core.utcdatetime.UTCDateTime :param starttime: Starttime for plotting, only used if debug > 2. :type samp_rate: float :param samp_rate: Sampling rate in Hz, only used for plotting if debug > 2. :return: peaks: Lists of tuples of peak values and locations. :rtype: list >>> import numpy as np >>> arr = np.random.randn(100) >>> threshold = 10 >>> arr[40] = 20 >>> arr[60] = 100 >>> find_peaks2_short(arr, threshold, 3) [(20.0, 40), (100.0, 60)] """ if not starttime: starttime = UTCDateTime(0) # Set everything below the threshold to zero image = np.copy(arr) image = np.abs(image) image[image < thresh] = 0 if len(image[image > thresh]) == 0: if debug > 0: print('No values over threshold found') return [] if debug > 0: print(' '.join(['Found', str(len(image[image > thresh])), 'samples above the threshold'])) initial_peaks = [] peaks = [] # Find the peaks labeled_image, number_of_objects = ndimage.label(image) peak_slices = ndimage.find_objects(labeled_image) for peak_slice in peak_slices: # print('Width of peak='+str(peak_slice[0].stop-peak_slice[0].start) window = arr[peak_slice[0].start: peak_slice[0].stop] initial_peaks.append((max(window), int(peak_slice[0].start + np.argmax(window)))) if initial_peaks: peaks = decluster(peaks=initial_peaks, trig_int=trig_int, debug=debug) if debug >= 3: from eqcorrscan.utils import plotting _fname = ''.join(['peaks_', starttime.datetime.strftime('%Y-%m-%d'), '.pdf']) plotting.peaks_plot(data=image, starttime=starttime, samp_rate=samp_rate, save=True, peaks=peaks, savefile=_fname) peaks = sorted(peaks, key=lambda time: time[1], reverse=False) return peaks else: print('No peaks for you!') return peaks
def decluster(peaks, trig_int, return_ind=False, debug=0): """ Decluster peaks based on an enforced minimum separation. :type peaks: list :param peaks: list of tuples of (value, sample) :type trig_int: int :param trig_int: Minimum trigger interval in samples :type return_ind: bool :param return_ind: Whether to also return the indices of the original peaks or not. :return: list of tuples of (value, sample) """ peaks_sort = sorted(zip(peaks, np.arange(len(peaks))), key=lambda amplitude: amplitude[0][0], reverse=True) peaks_sort, inds = zip(*peaks_sort) # Debugging if debug >= 4: for peak in peaks: print(peak) peaks_out = [] ind_out = [] add = False ind_out.append(inds[0]) peaks_out.append(peaks_sort[0]) # Definitely take the biggest peak if debug > 3: print(' '.join(['Added the biggest peak of', str(peaks_out[0][0]), 'at sample', str(peaks_out[0][1])])) if len(peaks) > 1: if debug > 3: msg = ' '.join(['Multiple peaks found, checking', 'them now to see if they overlap']) print(msg) for next_peak, next_ind in zip(peaks_sort, inds): # i in range(1,len(peaks_sort)): # Loop through the amplitude sorted peaks # if the next highest amplitude peak is within trig_int of any # peak already in peaks then we don't want it, else, add it # next_peak=peaks_sort[i] if debug > 3: print(next_peak) for peak in peaks_out: # Use add as a switch for whether or not to append # next peak to peaks, if once gone through all the peaks # it is True, then we will add it, otherwise we won't! if abs(next_peak[1] - peak[1]) < trig_int: if debug > 3: msg = ' '.join(['Difference in time is', str(next_peak[1] - peak[1]), '\n', 'Which is less than', str(trig_int)]) print(msg) add = False # Need to exit the loop here if false break else: add = True if add: if debug > 3: msg = ' '.join(['Adding peak of', str(next_peak[0]), 'at sample', str(next_peak[1])]) print(msg) ind_out.append(next_ind) peaks_out.append(next_peak) elif debug > 3: msg = ' '.join(['I did not add peak of', str(next_peak[0]), 'at sample', str(next_peak[1])]) print(msg) if return_ind: return peaks_out, ind_out else: return peaks_out
[docs]def coin_trig(peaks, stachans, samp_rate, moveout, min_trig, trig_int): """ Find network coincidence triggers within peaks of detection statistics. Useful for finding network detections from sets of detections on individual stations. :type peaks: list :param peaks: List of lists of tuples of (peak, index) for each \ station-channel. Index should be in samples. :type stachans: list :param stachans: List of tuples of (station, channel) in the order of \ peaks. :type samp_rate: float :param samp_rate: Sampling rate in Hz :type moveout: float :param moveout: Allowable network moveout in seconds. :type min_trig: int :param min_trig: Minimum station-channels required to declare a trigger. :type trig_int: float :param trig_int: Minimum allowable time between network triggers in seconds. :return: List of tuples of (peak, index), for the earliest detected station. :rtype: list >>> peaks = [[(0.5, 100), (0.3, 800)], [(0.4, 120), (0.7, 850)]] >>> triggers = coin_trig(peaks, [('a', 'Z'), ('b', 'Z')], 10, 3, 2, 1) >>> print(triggers) [(0.45, 100)] """ triggers = [] for stachan, _peaks in zip(stachans, peaks): for peak in _peaks: trigger = (peak[1], peak[0], '.'.join(stachan)) triggers.append(trigger) coincidence_triggers = [] for i, master in enumerate(triggers): slaves = triggers[i + 1:] coincidence = 1 trig_time = master[0] trig_val = master[1] for slave in slaves: if abs(slave[0] - master[0]) <= (moveout * samp_rate) and \ slave[2] != master[2]: coincidence += 1 if slave[0] < master[0]: trig_time = slave[0] trig_val += slave[1] if coincidence >= min_trig: coincidence_triggers.append((trig_val / coincidence, trig_time)) # Sort by trigger-value, largest to smallest - remove duplicate detections if coincidence_triggers: coincidence_triggers.sort(key=lambda tup: tup[0], reverse=True) output = [coincidence_triggers[0]] for coincidence_trigger in coincidence_triggers[1:]: add = True for peak in output: # If the event occurs within the trig_int time then do not add # it, and break out of the inner loop. if abs(coincidence_trigger[1] - peak[1]) < (trig_int * samp_rate): add = False break if add: output.append((coincidence_trigger[0], coincidence_trigger[1])) output.sort(key=lambda tup: tup[1]) return output else: return []
if __name__ == "__main__": import doctest doctest.testmod()