def test_fits_header_can_update_with_it(self, basic_pmh):
hdr = Header()
hdr.update(basic_pmh)
assert hdr["XTENSION"] == 'IMAGE'
assert hdr.comments["XTENSION"] == 'Image extension'
def model_to_table(model, xunit=None, yunit=None, zunit=None):
"""
Convert a model instance to a Table, suitable for attaching to an AstroData
object or interrogating.
Parameters
----------
model : a callable function , either a `~astropy.modeling.core.Model`
or a `~scipy.interpolate.BSpline` instance
xunit, yunit, zunit : Unit or None
unit of each axis (y axis may be dependent or independent variable)
Returns
-------
Table : a Table describing the model, with some information in the
meta["header"] dict
"""
# Override existing model units with new ones if requested
meta = getattr(model, "meta", {})
if xunit:
meta["xunit"] = xunit
if yunit:
meta["yunit"] = yunit
if zunit:
meta["zunit"] = zunit
model_class = model.__class__.__name__
if isinstance(model, Model):
header = Header({"MODEL": model_class})
ndim = model.n_inputs
if ndim == 1:
if getattr(model, "domain", None) is not None:
header.update({
"DOMAIN_START": model.domain[0],
"DOMAIN_END": model.domain[1]
})
elif ndim == 2:
if getattr(model, "x_domain", None) is not None:
header.update({
"XDOMAIN_START": model.x_domain[0],
"XDOMAIN_END": model.x_domain[1]
})
if getattr(model, "y_domain", None) is not None:
header.update({
"YDOMAIN_START": model.y_domain[0],
"YDOMAIN_END": model.y_domain[1]
})
else:
raise ValueError(f"Cannot handle model class '{model_class}' "
f"with dimensionality {ndim}")
table = Table(model.parameters, names=model.param_names)
for unit in ("xunit", "yunit", "zunit"):
if unit in meta:
header[unit.upper()] = (str(meta[unit]),
f"Units of {unit[0]} axis")
elif isinstance(model, BSpline):
knots, coeffs, order = model.tck
header = Header({"MODEL": f"spline{order}"})
table = Table([knots, coeffs],
names=("knots", "coefficients"),
units=(meta.get("xunit"), meta.get("yunit")))
else:
raise TypeError(f"Cannot convert object of class '{model_class}'")
table.meta["header"] = header
return table
