def write_stream_to_sac(str1, write_dir='data', ext='', verbose=False):
if ext != '':
ext = '.' + ext
if not os.path.isdir(write_dir):
sys.exit('No such dir to write sac', write_dir)
for tr in str1:
sac = AttribDict()
(sac.kstnm, sac.knetwk, sac.kcmpnm,
sac.khole) = (str(tr.stats.station), str(tr.stats.network),
str(tr.stats.channel), str(tr.stats.location))
(sac.stla, sac.stlo,
sac.stel) = (tr.stats.station_coordinates.latitude,
tr.stats.station_coordinates.longitude,
tr.stats.station_coordinates.elevation)
ev = tr.stats.event_origin
time = ev.time
# sac depth is in km
sac.evla, sac.evlo, sac.evdp, sac.mag = ev.latitude, ev.longitude, ev.depth / 1000., tr.stats.event_mag.mag
sac.evla, sac.evlo, sac.evdp, sac.mag = ev.latitude, ev.longitude, ev.depth / 1000., tr.stats.event_mag.mag
# sac uses millisec while obspy uses microsec.
sac.nzyear, sac.nzjday, sac.nzhour, sac.nzmin, sac.nzsec, sac.nzmsec = time.year, time.julday, time.hour, time.minute, time.second, time.microsecond / 1000
sac.o = 0.
sac.b = tr.stats.starttime - time # this is very important!!
sac.kevnm = str(time)
# dip is from horizontal downward; inc is from vertical downward
# in SAC component "incidence angle" relative to the vertical
sac.cmpaz, sac.cmpinc = tr.stats.cmpaz, tr.stats.dip + 90
sac.gcarc, sac.dist, sac.az, sac.baz = tr.stats.gcarc, tr.stats.distance / 1000, tr.stats.azimuth, tr.stats.back_azimuth
# traveltimes
sac.a = tr.stats.Parr.arrival_time
sac.ka = 'P' # cannot add S time because user1 is assigned to ray parameter
# the ray parameter required by hk code is in sin(th)/v
(sac.user0, sac.user1) = (tr.stats.Parr.rayp / radiusOfEarth,
tr.stats.Sarr.rayp / radiusOfEarth)
# add sac header to tr.stats
tr.stats.sac = sac
# set sac file name
tr_name = write_dir + '/' + tr.stats.station + '.' + tr.stats.network + '.' + tr.stats.location + '.' + tr.stats.channel + ext + '.sac'
tr.write(tr_name, format='SAC')
if verbose:
print('Writing sac file ...' + tr_name)
