def species(self, element, ion, **kwargs):
"""
Homogenise the line abundances for all stars for a given element and ion.
:param element:
The element name to homogenise.
:type element:
str
:param ion:
The ionisation stage of the element to homogenise (1 = neutral).
:type ion:
int
"""
scaled = kwargs.get("scaled", True)
# Remove any existing homogenised line or average abundances.
self.release.execute("""DELETE FROM homogenised_line_abundances
WHERE TRIM(element) = %s AND ion = %s""", (element, ion))
self.release.execute("""DELETE FROM homogenised_abundances
WHERE TRIM(element) = %s AND ion = %s""", (element, ion))
# Drop index if it exists.
self.release.execute(
"DROP INDEX IF EXISTS homogenised_line_abundances_species_index")
self.release.commit()
# Get the unique wavelengths.
wavelengths = sorted(set(self.release.retrieve_table(
"""SELECT DISTINCT ON (wavelength) wavelength FROM line_abundances
WHERE TRIM(element) = %s AND ion = %s AND flags = 0
ORDER BY wavelength ASC""", (element, ion))["wavelength"]))
# Get the unique CNAMEs. We deal with repeat spectra (of the same CNAME)
# later on in the code.
cnames = self.release.retrieve_table(
"""SELECT DISTINCT ON (cname) cname FROM line_abundances
WHERE TRIM(element) = %s AND ion = %s ORDER BY cname ASC""",
(element, ion))["cname"]
# For each wavelength, approximate the covariance matrix then homogenise
# this wavelength for all cnames.
column = "scaled_abundance" if scaled else "abundance"
logger.debug("Homogenising {0} {1} using column {2}".format(element,
ion, column))
# In order to build the covariance matrix for this species, at some
# point we will need to know the variance for each line. We can estimate
# this from the variance in the distribution of differential abundances.
# This effectively tells us how well this line could have been measured
# (after accounting for systematics between different nodes).
Y, Y_nodes, Y_table = self.release._match_species_abundances(
element, ion, scaled=scaled, include_flagged_lines=False)
# Homogenise the line abundances for each wavelength separately.
for i, wavelength in enumerate(sorted(set(wavelengths))):
# Match all of the abundances for this given line, so that we can
# use the array to calculate the correlation coefficients between
# different nodes for this particular line.
X, X_nodes = self.release._match_line_abundances(element, ion,
wavelength, column, ignore_gaps=True, include_limits=False,
include_flagged_lines=False, **kwargs)
# Get the measurement variance for this line.
Z = utils.calculate_differential_abundances(
Y[(Y_table["wavelength"] == wavelength)])
line_variance = np.nanvar(np.abs(Z))
if not np.isfinite(line_variance):
# If the line variance is not finite, it means we do not have
# differential abundances for this line. This is typically
# because there were not enough nodes measuring this wavelength.
# But we do know where this line sits with respect to the mean
# abundance for this element. So we can still estimate the line
# variance.
assert Y.shape[1] > 1
# For each measured wavelength, what is the mean abundance for
# the corresponding star, and what is the variance in that
# distribution?
matchers = []
wl_mask = (Y_table["wavelength"] == wavelength)
for stub in Y_table["spectrum_filename_stub"][wl_mask]:
stub_mask = (Y_table["spectrum_filename_stub"] == stub)
value = Y[stub_mask*wl_mask].flatten()
node_mask = np.isfinite(value)
value = value[node_mask]
matchers.extend(Y[stub_mask * ~wl_mask, node_mask] - value)
line_variance = np.nanvar(np.abs(matchers))
if line_variance == 0:
# This line was only measured by one node in some stars, and
# in those stars there are no other measurements of this
# element, so we have no basis for the variance in this line
# This is a fringe case, and we will just have to do
# something reasonable:
line_variance = kwargs.get("default_variance", 0.1**2)
logger.warn("Using default variance of {0:.2f} for {1} {2}"\
" line at {3}".format(line_variance, element, ion,
wavelength))
assert np.isfinite(line_variance) and line_variance > 0
# For each CNAME / FILENAME, homogenise this line.
for j, cname in enumerate(cnames):
# The line_abundances function will need the element, ion,
# wavelength, the variance in the line measurement, and the
# correlation coefficients between nodes (or the matrix to
# produce them), and the cname to know where to put things.
result = self.line_abundances(cname, element, ion, wavelength,
line_variance, X, X_nodes)
# Need to commit before we can do the averaged results per star.
self.release.commit()
# Create an index to speed things up.
# To prevent parallel problems, first check that the index has not been
# created by a parallel homogenisation script.
try:
self.release.execute("""CREATE INDEX
homogenised_line_abundances_species_index
ON homogenised_line_abundances (cname, element, ion)""")
self.release.commit()
except:
self.release.execute("rollback")
# To homogenise the spectrum abundances, we will need the correlation
# coefficients between each line.
# Match the homogenised line abundances on a per-star basis.
Q, Q_wavelengths = self.release._match_homogenised_line_abundances(
element, ion, ignore_gaps=False, include_limits=False)
Q_rho = np.atleast_2d(np.ma.corrcoef(Q))
for j, cname in enumerate(cnames):
self.spectrum_abundances(element, ion, cname, rho=Q_rho,
rho_wavelengths=Q_wavelengths, **kwargs)
self.release.commit()
# TODO what should we return?
return None
def differential(self, element, ion, scaled=False, ignore_flags=False,
**kwargs):
"""
Calculate the differential abundance bias for each wavelength for each
node.
:param element:
The element name to homogenise.
:type element:
str
:param ion:
The ionisation stage of the element to homogenise (1 = neutral).
:type ion:
int
"""
X, nodes, diff_data = self.release._match_species_abundances(
element, ion, scaled=scaled, include_flagged_lines=~ignore_flags)
#X, nodes, diff_data = utils.match_node_abundances(self.release._database,
# element, ion, scaled=scaled, ignore_flags=ignore_flags)
# Calculate the full differential abundances.
X_diff, indices = utils.calculate_differential_abundances(X,
full_output=True)
# Determine the differences to each node.
diff_data["wavelength"] = diff_data["wavelength"].astype(float)
wavelengths = sorted(set(diff_data["wavelength"]))
bias = { n: { w: (0, np.nan, -1) for w in wavelengths } for n in nodes }
for wavelength in wavelengths:
X_wl = X_diff[(diff_data["wavelength"] == wavelength), :]
finite = { node: 0 for node in nodes }
for k, (i, j) in enumerate(indices):
value = np.isfinite(X_wl[:, k]).sum()
finite[nodes[i]] += value
finite[nodes[j]] += value
finite_nodes = [node for node in nodes if finite[node] > 0]
def differential_sigma(biases):
# Apply the biases on a per-column basis.
X_offsets = np.zeros(X_wl.shape[1])
for i, idx in enumerate(indices):
# These are Node_0 - Node_1
# We want to apply (Node_0 - offset_0) - (Node_1 - offset_1)
# so the total offset is offset_1 - offset_0
# The biases.size is related to finite_nodes, not nodes.
try:
jdx0 = finite_nodes.index(nodes[idx[0]])
jdx1 = finite_nodes.index(nodes[idx[1]])
except ValueError:
continue
else:
X_offsets[i] = biases[jdx1] - biases[jdx0]
return np.nanstd(X_wl - X_offsets)
result = op.fmin(differential_sigma, np.zeros(len(finite_nodes)),
disp=False)
initial = differential_sigma(np.zeros(len(finite_nodes)))
final = differential_sigma(result)
logger.info("Initial and final sigma: {0:.2f} {1:.2f}".format(
initial, final))
for node, offset in zip(finite_nodes, result):
bias[node][wavelength] = (-offset, np.nan, -1)
return bias
