def calc_timeshift(self, st_b, allow_negative_CC=False):
"""
dt_all, CC = calc_timeshift(self, st_b, allow_negative_CC)
Calculate timeshift between two waveforms using the maximum of the
cross-correlation function.
Parameters
----------
self : obspy.Stream
Stream that contains the reference traces
st_b : obspy.Stream
Stream that contains the traces to compare
allow_negative_CC : boolean
Pick the maximum of the absolute values of CC(t). Useful,
if polarity may be wrong.
Returns
-------
dt_all : dict
Dictionary with entries station.location and the estimated
time shift in seconds.
CC : dict
Dictionary with the correlation coefficients for each station.
"""
dt_all = dict()
CC_all = dict()
for tr_a in self:
try:
tr_b = st_b.select(station=tr_a.stats.station,
location=tr_a.stats.location)[0]
corr = signal.correlate(tr_a.data, tr_b.data)
if allow_negative_CC:
idx_CCmax = np.argmax(abs(corr))
CC = abs(corr[idx_CCmax])
else:
idx_CCmax = np.argmax(corr)
CC = corr[idx_CCmax]
dt = (idx_CCmax - tr_a.stats.npts + 1) * tr_a.stats.delta
CC /= np.sqrt(np.sum(tr_a.data**2) * np.sum(tr_b.data**2))
# print('%s.%s: %4.1f sec, CC: %f' %
# (tr_a.stats.station, tr_a.stats.location, dt, CC))
code = '%s.%s' % (tr_a.stats.station, tr_a.stats.location)
dt_all[code] = dt
CC_all[code] = CC
except IndexError:
print('Did not find %s' % (tr_a.stats.station))
return dt_all, CC_all
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