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Jeremy M Fee
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"""Convert streams from one coordinate system to another.
We use three coordinate systems.
Geo: Based on Geographic North. X, Y, Z, F
X is north, Y is east, Z is down
Obs: Based on the observatories orientaion. H, E, Z, F, d0
Mag: Based on Magnetic North. H, D, Z, F
"""
Jeremy M Fee
committed
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import obspy.core
import ChannelConverter
def get_geo_from_mag(mag):
pass
def get_geo_from_obs(obs):
"""Convert a stream to geographic coordinate system.
Parameters
----------
stream : obspy.core.Stream
stream containing observatory components H, D or E, Z, and F.
Returns
-------
obspy.core.Stream
new stream object containing geographic components X, Y, Z, and F.
"""
return get_geo_from_mag(get_mag_from_obs(obs))
def get_mag_from_geo(geo):
pass
def get_mag_from_obs(obs):
"""Convert a stream to magnetic coordinate system.
Parameters
----------
obs : obspy.core.Stream
stream containing observatory components H, D or E, Z, and F.
Returns
-------
obspy.core.Stream
new stream object containing magnetic components H, D, Z, and F.
"""
h = obs.select(channel='H')[0]
d = __get_obs_d_from_obs(obs)
z = obs.select(channel='Z')[0]
f = obs.select(channel='F')[0]
obs_h = h.data
obs_d = d.data
d0 = ChannelConverter.get_radians_from_minutes(
numpy.float64(d.stats['DECBAS']) / 10)
(mag_h, mag_d) = ChannelConverter.get_mag_from_obs(obs_h, obs_d, d0)
return obspy.core.Stream((
__get_trace('H', h.stats, mag_h),
__get_trace('D', d.stats, mag_d),
z, f))
def get_obs_from_geo(geo, include_e=False):
"""Convert a stream to geographic coordinate system.
Parameters
----------
stream : obspy.core.Stream
stream containing geographic components X, Y, Z, and F.
include_e : boolean
whether to also include the observatory E component.
Returns
-------
obspy.core.Stream
new stream object containing observatory components H, D, E, Z, and F.
"""
return get_obs_from_mag(get_mag_from_geo(geo))
def get_obs_from_mag(mag, include_e=False):
# TODO
obs = obspy.core.Stream()
if include_e:
obs += __get_obs_e_from_obs(obs)
return obs
def __get_trace(channel, stats, data):
"""Utility to create a new trace object.
Parameters
----------
channel : str
channel name.
stats : obspy.core.Stats
channel metadata to clone.
data : numpy.array
channel data.
Returns
-------
obspy.core.Trace
trace containing data and metadata.
"""
stats = obspy.core.Stats(stats)
stats.channel = channel
return obspy.core.Trace(data, stats)
def __get_obs_d_from_obs(obs):
"""Get trace containing observatory D component.
Returns D if found, otherwise computes D from H, E, D0.
Parameters
----------
obs : obspy.core.Stream
observatory components (D) or (H, E).
Returns
-------
obspy.core.Trace
observatory component D.
"""
try:
d = obs.select(channel='D')[0]
except:
h = obs.select(channel='H')[0]
e = obs.select(channel='E')[0]
d = __get_trace('D', e.stats,
ChannelConverter.get_obs_d_from_obs(h.data, e.data))
return d
def __get_obs_e_from_obs(obs):
"""Get trace containing observatory E component.
Returns E if found, otherwise computes E from H,D.
Parameters
----------
obs : obspy.core.Stream
observatory components (E) or (H, D).
Returns
-------
obspy.core.Trace
observatory component E.
"""
try:
e = obs.select(channel='E')[0]
except:
h = obs.select(channel='H')[0]
d = obs.select(channel='D')[0]
e = __get_trace('E', d.stats,
ChannelConverter.get_obs_e_from_obs(h.data, d.data))
return e