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ift
NIFTy
Commits
1bb2c55c
Commit
1bb2c55c
authored
Feb 18, 2019
by
Martin Reinecke
Committed by
Lukas Platz
Feb 18, 2019
Browse files
Added Martin's 'apply_spherical_convolution' function as template
parent
9e644972
Changes
1
Hide whitespace changes
Inline
Side-by-side
nifty5/domains/lm_space.py
View file @
1bb2c55c
...
...
@@ -147,3 +147,40 @@ class LMSpace(StructuredDomain):
from
..domains.hp_space
import
HPSpace
if
not
isinstance
(
codomain
,
(
GLSpace
,
HPSpace
)):
raise
TypeError
(
"codomain must be a GLSpace or HPSpace."
)
def
apply_spherical_convolution
(
inp
,
func
):
"""Convolves `inp` with a kernel defined by `func`
which is assumed to be radially symmetric around theta==0."""
import
pyHealpix
from
.gl_space
import
GLSpace
from
..operators.harmonic_operators
import
HarmonicTransformOperator
if
len
(
inp
.
domain
)
!=
1
:
raise
ValueError
(
"need exactly one domain"
)
sph
=
inp
.
domain
[
0
]
# define an appropriate harmonic partner space
lm
=
sph
.
get_default_codomain
()
if
not
isinstance
(
lm
,
LMSpace
):
raise
TypeError
(
"need a spherical domain"
)
# define azimuthally symmetric spaces for kernel transform
gl
=
GLSpace
(
lm
.
lmax
+
1
,
1
)
lm0
=
gl
.
get_default_codomain
()
theta
=
pyHealpix
.
GL_thetas
(
gl
.
nlat
)
# evaluate the kernel function at the required thetas
kernel_sphere
=
Field
.
from_global_data
(
gl
,
func
(
theta
))
# normalize the kernel such that the integral over the sphere is 4pi
kernel_sphere
=
kernel_sphere
*
(
4
*
np
.
pi
/
kernel_sphere
.
integrate
())
# compute the spherical harmonic coefficients of the kernel
op
=
HarmonicTransformOperator
(
lm0
,
gl
)
kernel_lm
=
op
.
adjoint_times
(
kernel_sphere
.
weight
(
1
)).
to_global_data
()
# evaluate the k lengths of the harmonic space
k_lengths
=
lm
.
get_k_length_array
().
to_global_data
().
astype
(
np
.
int
)
op
=
HarmonicTransformOperator
(
lm
,
sph
)
# "inverse" transform to harmonic space
inp_lm
=
op
.
adjoint_times
(
inp
.
weight
(
1
)).
to_global_data
()
# multiply the kernel to the coefficients and adjust normalization
inp_lm
=
inp_lm
*
kernel_lm
[
k_lengths
]
*
4
*
np
.
pi
out
=
Field
.
from_global_data
(
lm
,
inp_lm
)
# back to the original space
return
op
(
out
)
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