def advected_field(cat, field_late, weight, nmesh):
'''
Get the advected component field with the weights given by the 'weight' column.
Input:
-cat: catalog of galaxy positions, assumed to have dimensions [3, N] right now
-field_late: late-time density field (the delta_1 component) which is needed to
prevent an nbodykit bug when placing down weights
-weight: the early time component field used for the weights. See Note about 1-1 mapping
-nmesh: Nmesh for the late-time advected field. Can be different from the grid value of the component field.
Output:
-field_complate: late-time, advected component field for the given input weights.
Notes: In ZAemulus it's assumed that there's a clear 1-1 mapping between positions
and particle since this comes from reshaping the grids. This has to be changed for
a more realistic particle catalog.
'''
Lbox = field_late.BoxSize[0]
nbodycat = np.empty(nmesh**3,
dtype=[('Position', ('f8', 3)), ('Weight', 'f8')])
nbodycat['Position'] = cat.T
#Collapse the weight grids into catalog shape.
#Need to change this for future runs.
#+1 is needed if subtracting from field_late
nbodycat['Weight'] = weight.value.reshape(nmesh**3) + 1
nbkcat = ArrayCatalog(nbodycat, Nmesh=nmesh, BoxSize=Lbox)
mesh = nbkcat.to_mesh(Nmesh=nmesh, BoxSize=Lbox, weight='Weight')
#Paint and subtract from late field to avoid annoying nbodykit bugs
field_component_late = (mesh.paint(mode='real') - 1)
field_component_late -= field_late
return field_component_late
def cat_to_mesh(cat, Lbox, Nmesh):
'''
Convert the late-time particle catalog to a friendly neighbourhood mesh
Input:
-cat: format is [Npos, Nparticles]
-Lbox: units are Mpc/h
-Nmesh: size of mesh you want to deposit particles in
Output:
-mesh
'''
nbodycat = np.empty(nmesh**3, dtype=[('Position', ('f8', 3))])
nbodycat['Position'] = cat.T
nbkcat = ArrayCatalog(nbodycat, Nmesh=nmesh, BoxSize=Lbox)
mesh = nbkcat.to_mesh(Nmesh=nmesh, BoxSize=Lbox)
field = (mesh.paint(mode='real') - 1)
return field
f = ArrayCatalog(data)
print(f)
print("columns = ", f.columns) # default Weight,Selection also present
print("total size = ", f.csize)
f = ArrayCatalog({'Position': data['Position'], 'Mass': data['Mass']})
print(f)
print("columns = ", f.columns) # default Weight,Selection also present
print("total size = ", f.csize)
# convert to a MeshSource, using CIC interpolation on 1280^3 mesh
mesh = f.to_mesh(window='cic',
Nmesh=1280,
BoxSize=4000.0,
compensated=True,
interlaced=True)
rfield = mesh.compute()
cfield = (rfield - 1).r2c()
cfield_real = np.zeros((1280, 1280, 641), dtype=float)
cfield_imag = np.zeros((1280, 1280, 641), dtype=float)
for i in np.arange(1280):
print(i)
for j in np.arange(1280):
for k in np.arange(641):
cfield_real[i][j][k] = cfield[i][j][k].real
cfield_imag[i][j][k] = cfield[i][j][k].imag