def Transform(obj,
jac=(1., 0., 0., 1.),
offset=galsim.PositionD(0., 0.),
flux_ratio=1.,
gsparams=None):
"""A function for transforming either a GSObject or ChromaticObject.
This function will inspect its input argument to decide if a Transformation object or a
ChromaticTransformation object is required to represent the resulting transformed object.
@param obj The object to be transformed.
@param jac A list or tuple ( dudx, dudy, dvdx, dvdy ) describing the Jacobian
of the transformation. [default: (1,0,0,1)]
@param offset A galsim.PositionD giving the offset by which to shift the profile.
@param flux_ratio A factor by which to multiply the flux of the object. [default: 1]
@param gsparams An optional GSParams argument. See the docstring for GSParams for
details. [default: None]
@returns a Transformation or ChromaticTransformation instance as appropriate.
"""
if not (isinstance(obj, galsim.GSObject)
or isinstance(obj, galsim.ChromaticObject)):
raise TypeError(
"Argument to Transform must be either a GSObject or a ChromaticObject."
)
elif (hasattr(jac, '__call__') or hasattr(offset, '__call__')
or hasattr(flux_ratio, '__call__')
or isinstance(obj, galsim.ChromaticObject)):
# Sometimes for Chromatic compound types, it is more efficient to apply the
# transformation to the components rather than the whole. In particular, this can
# help preserve separability in many cases.
# Don't transform ChromaticSum object, better to just transform the arguments.
if isinstance(obj, galsim.ChromaticSum) or isinstance(obj, galsim.Sum):
return galsim.ChromaticSum([
Transform(o, jac, offset, flux_ratio, gsparams)
for o in obj.objlist
])
# If we are just flux scaling, then a Convolution can do that to the first element.
# NB. Even better, if the flux scaling is chromatic, would be to find a component
# that is already non-separable. But we don't bother trying to do that currently.
elif (isinstance(
obj, galsim.ChromaticConvolution
or isinstance(obj, galsim.Convolution))
and np.array_equal(np.asarray(jac).ravel(), (1, 0, 0, 1))
and offset == galsim.PositionD(0., 0.)):
first = Transform(obj.objlist[0],
flux_ratio=flux_ratio,
gsparams=gsparams)
return galsim.ChromaticConvolution([first] +
[o for o in obj.objlist[1:]])
else:
return galsim.ChromaticTransformation(obj, jac, offset, flux_ratio,
gsparams)
else:
return Transformation(obj, jac, offset, flux_ratio, gsparams)
def Add(*args, **kwargs):
"""A function for adding 2 or more GSObject or ChromaticObject instances.
This function will inspect its input arguments to decide if a Sum object or a
ChromaticSum object is required to represent the sum of surface brightness profiles.
Typically, you do not need to call Add() explicitly. Normally, you would just use the +
operator, which returns a Sum:
>>> bulge = galsim.Sersic(n=3, half_light_radius=0.8)
>>> disk = galsim.Exponential(half_light_radius=1.4)
>>> gal = bulge + disk
>>> psf = galsim.Gaussian(sigma=0.3, flux=0.3) + galsim.Gaussian(sigma=0.8, flux=0.7)
If one of the items is chromatic, it will return a ChromaticSum
>>> disk = galsim.Exponential(half_light_radius=1.4) * galsim.SED(sed_file)
>>> gal = bulge + disk
@param args Unnamed args should be a list of objects to add.
@param gsparams An optional GSParams argument. See the docstring for GSParams for
details. [default: None]
@returns a Sum or ChromaticSum instance as appropriate.
"""
if len(args) == 0:
raise ValueError(
"At least one ChromaticObject or GSObject must be provided.")
elif len(args) == 1:
# 1 argument. Should be either a GSObject or a list of GSObjects
if isinstance(args[0], (galsim.GSObject, galsim.ChromaticObject)):
args = [args[0]]
elif isinstance(args[0], list):
args = args[0]
else:
raise TypeError(
"Single input argument must be a GSObject, ChromaticObject or "
+ "a (possibly mixed) list of them.")
# else args is already the list of objects
if any([isinstance(a, galsim.ChromaticObject) for a in args]):
return galsim.ChromaticSum(*args, **kwargs)
else:
return Sum(*args, **kwargs)