def test_get_obs_from_geo(self):
"""geomag.io.channelTest.test_get_obs_from_geo()
The geographic north and east components ``X`` and ``Y`` of the
magnetic field vector H, combined with the declination baseline angle
``d0`` can be used to produce the observatory components ``h`` and
```e``
"""
# 1) Call get_obs_from_geo using equal X,Y values with a d0 of 0
# the observatory values h,e will be the same.
X = 1
Y = 1
(h, e) = channel.get_obs_from_geo(X, Y)
assert_almost_equal(h, 1.0, 8, 'Expect h to be 1.', True)
assert_almost_equal(e, 1.0, 8, 'Expect e to be 1.', True)
# 2) Call get_obs_from_geo using equal X,Y values to create a 45
# degree angle (D), with a d0 of 45/2. The observatory declination
# (d) will be 45/2, the difference between the total field angle,
# and d0.
X = 1
Y = 1
d0 = 22.5 * D2R
(h, e) = channel.get_obs_from_geo(X, Y, d0)
d = channel.get_obs_d_from_obs(h, e)
assert_almost_equal(d, 22.5 * D2R, 8,
'Expect d to be 22.5 degrees.', True)
# 3) Call get_obs_from_geo using equal X,Y values to create a 45
# degree angle (D), with a d0 of 315 degrees. The observatory
# declination (d) will be 90 degrees.
X = 1
Y = 1
d0 = 315 * D2R
(h, e) = channel.get_obs_from_geo(X, Y, d0)
d = channel.get_obs_d_from_obs(h, e)
assert_almost_equal(d, 90 * D2R, 8, 'Expect d to be 90 degrees.', True)
# 4) Call get_obs_from_geo using X,Y values of cos(60), sin(60), and
# d0 of 30 degrees. The observatory values h,e will be cos(30)
# and sin(30), and the observatory declination will be 30 degrees.
# The observatory angle of 30 degrees + the d0 of 30 degrees produces
# the total declination (D) of 60 degrees.
X = cos(60 * D2R)
Y = sin(60 * D2R)
d0 = 30 * D2R
(h, e) = channel.get_obs_from_geo(X, Y, d0)
assert_almost_equal(h, cos(30 * D2R), 8,
'Expect h to be cos(30).', True)
assert_almost_equal(e, sin(30 * D2R), 8,
'Expect e to be sin(30).', True)
d = channel.get_obs_d_from_obs(h, e)
assert_almost_equal(d, 30 * D2R, 8, 'Expect d to be 30 degrees.', True)
def get_obs_from_mag(mag, include_d=False):
"""Convert a stream to magnetic observatory coordinate system.
Parameters
----------
stream: obspy.core.Stream
stream containing magnetic components H, D, Z, and F.
include_d: boolean
whether to also include the observatory D component
Returns
-------
obspy.core.Stream
new stream object containing observatory components H, D, E, Z, and F
"""
h = mag.select(channel='H')[0]
d = mag.select(channel='D')[0]
z = mag.select(channel='Z')[0]
f = mag.select(channel='F')[0]
mag_h = h.data
mag_d = d.data
d0 = ChannelConverter.get_radians_from_minutes(
numpy.float64(d.stats.declination_base) / 10)
(obs_h, obs_e) = ChannelConverter.get_obs_from_mag(mag_h, mag_d, d0)
traces = (
__get_trace('H', h.stats, obs_h),
__get_trace('E', d.stats, obs_e),
z, f)
if include_d:
obs_d = ChannelConverter.get_obs_d_from_obs(obs_h, obs_e)
traces = traces + (__get_trace('D', d.stats, obs_d),)
return obspy.core.Stream(traces)
def get_obs_from_mag(mag, include_d=False):
"""Convert a stream to magnetic observatory coordinate system.
Parameters
----------
stream: obspy.core.Stream
stream containing magnetic components H, D, Z, and F.
include_d: boolean
whether to also include the observatory D component
Returns
-------
obspy.core.Stream
new stream object containing observatory components H, D, E, Z, and F
"""
h = mag.select(channel='H')[0]
d = mag.select(channel='D')[0]
z = mag.select(channel='Z')[0]
f = mag.select(channel='F')[0]
mag_h = h.data
mag_d = d.data
d0 = ChannelConverter.get_radians_from_minutes(
numpy.float64(d.stats.declination_base) / 10)
(obs_h, obs_e) = ChannelConverter.get_obs_from_mag(mag_h, mag_d, d0)
traces = (__get_trace('H', h.stats,
obs_h), __get_trace('E', d.stats, obs_e), z, f)
if include_d:
obs_d = ChannelConverter.get_obs_d_from_obs(obs_h, obs_e)
traces = traces + (__get_trace('D', d.stats, obs_d), )
return obspy.core.Stream(traces)
def test_get_obs_d_from_obs(self):
"""geomag.ChannelConverterTest.test_get_obs_d_from_obs()
``d`` is the angle formed by the observatory components ``h`` and
``e`` the primary and secondary axis of the horizontal magnetic
field vector in the observatories frame of reference.
"""
# 1) Call get_obs_d_from_obs usine h,e equal to cos(30), sin(30).
# Expect d to be 30.
h = cos(30 * D2R)
e = sin(30 * D2R)
d = channel.get_obs_d_from_obs(h, e)
assert_almost_equal(d, 30 * D2R, 8, 'Expect d to be 30 degrees.', True)
# 2) Call get_obs_d_from_obs using h,e cos(30), -sin(30). Expect
# d to be 30.
h = cos(30 * D2R)
e = sin(-30 * D2R)
d = channel.get_obs_d_from_obs(h, e)
assert_almost_equal(d, -30 * D2R, 8,
'Expect d to be 30 degrees.', True)
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_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
