GGGCorrelation: Shear-Shear-Shear Correlations

The GGGCorrelation class computes the three‑point correlation of spin-2 fields.

Example

import orpheus

cat = orpheus.SpinTracerCatalog(
    spin=2, pos1=x, pos2=y, tracer_1=g1, tracer_2=g2)
ggg = orpheus.GGGCorrelation(
    n_cfs=4, min_sep=1., max_sep=128., binsize=0.1, nthreads=nthreads)
ggg.process(cat)      # Compute 3PCF in multipole basis
ggg.multipoles2npcf() # Transform to real-space basis

class orpheus.GGGCorrelation(n_cfs, min_sep, max_sep, **kwargs)

Bases: BinnedNPCF

Class containing methods to measure and obtain statistics that are built from third-order shear correlation functions.

n_cfs

The number of independent components of the NPCF.

Type

int

min_sep

The smallest distance of each vertex for which the NPCF is computed.

Type

float

max_sep

The largest distance of each vertex for which the NPCF is computed.

Type

float

Notes

Inherits all other parameters and attributes from BinnedNPCF. Additional child-specific parameters can be passed via kwargs. Either nbinsr or binsize has to be provided to fix the binning scheme.

saveinst(path_save, fname)

__process_patches(cat, dotomo=True, rotsignflip=False, apply_edge_correction=False, adjust_tree=False, save_patchres=False, save_filebase='', keep_patchres=False)

process(cat, dotomo=True, rotsignflip=False, apply_edge_correction=False, adjust_tree=False, save_patchres=False, save_filebase='', keep_patchres=False)

Compute a shear 3PCF provided a shape catalog

Parameters

• cat (orpheus.SpinTracerCatalog) – The shape catalog which is processed

• dotomo (bool) – Flag that decides whether the tomographic information in the shape catalog should be used. Defaults to True.

• rotsignflip (bool) – If the shape catalog has been decomposed in patches, choose whether the rotation angle should be flipped. For simulated data this was always ok to set to False. Defaults to False.

• apply_edge_correction (bool) – Flag that decides how the NPCF in the real space basis is computed. * If set to True the computation is done via edge-correcting the GGG-multipoles * If set to False both GGG and NNN are transformed separately and the ratio is done in the real-space basis Defaults to False.

• adjust_tree (bool) – Overrides the original setup of the tree-approximations in the instance based on the nbar of the shape catalog. Not implemented yet; has no effect. Defaults to False.

• save_patchres (bool or str) – If the shape catalog has been decomposed in patches, flag whether to save the GGG measurements on the individual patches. Note that the path needs to exist, otherwise a ValueError is raised. For a flat-sky catalog this parameter has no effect. Defaults to False.

• save_filebase (str) – Base of the filenames in which the patches are saved. The full filename will be <save_patchres>/<save_filebase>_patchxx.npz. Only has an effect if the shape catalog consists of multiple patches and save_patchres is not False.

• keep_patchres (bool) – If the catalog consists of multiple patches, returns all measurements on the patches. Defaults to False.

edge_correction(ret_matrices=False)

_multipoles2npcf_py()

multipoles2npcf(projection='Centroid')

Notes

The Upsilon and Norms are only computed for the n>0 multipoles. The n<0 multipoles are recovered by symmetry considerations given in Eq A.6 in Porth+23.

projectnpcf(projection)

_x2centroid()

computeMap3(radii, do_multiscale=False, tofile=False, filtercache=None)

Compute third-order aperture statistics using the polynomial filter.

_map3_filtergrid_singleR(R1, R2, R3)

__map3_filtergrid_singleR(R2, R3, normys_edges, normys_centers, phis)

_map3_filtergrid_multiR(R1, R2, R3)

__map3_filtergrid_multiR(R2, R3, normys_edges, normys_centers, phis, include_measure=True)

_checkcats(cats, spins)

_initprojections(child)

_print_npcfprojections_avail(child)

_projectnpcf(child, projection)

Projects npcf to a new basis.

_updatetree(new_resos, include_shifts=True)

autoset_tree(cat, dpix_grid=2.0, nside_grid=2048)