minhmpa/pyrecon

package for BAO reconstruction as used by DESI

pyrecon - Python reconstruction code

Introduction

pyrecon is a package to perform reconstruction within Python, using different algorithms, so far:

• MultiGridReconstruction, based on Martin J. White's code https://github.com/martinjameswhite/recon_code
• IterativeFFTParticleReconstruction, based on Julian E. Bautista's code https://github.com/julianbautista/eboss_clustering/blob/master/python/recon.py
• IterativeFFTReconstruction, iterative algorithm of Burden et al. 2015 (https://arxiv.org/abs/1504.02591) at the field-level (as opposed to IterativeFFTParticleReconstruction)
• PlaneParallelFFTReconstruction, base algorithm of Eisenstein et al. 2007 (https://arxiv.org/pdf/astro-ph/0604362.pdf), in the plane-parallel approximation.

With Python, a typical reconstruction run is (e.g. for MultiGridReconstruction; the same works for other algorithms):

from pyrecon import MultiGridReconstruction

# line-of-sight "los" can be local (None, default) or an axis, 'x', 'y', 'z', or a 3-vector
# Instead of boxsize and boxcenter, one can provide a (N, 3) array of Cartesian positions: positions=
recon = MultiGridReconstruction(f=0.8, bias=2.0, los=None, nmesh=512, boxsize=1000., boxcenter=2000.)
recon.assign_data(data_positions, data_weights) # data_positions is a (N, 3) array of Cartesian positions, data_weights a (N,) array
# You can skip the following line if you assume uniform selection function (randoms)
recon.assign_randoms(randoms_positions, randoms_weights)
recon.set_density_contrast(smoothing_radius=15.)
recon.run()
# If you are using IterativeFFTParticleReconstruction, displacements are to be taken at the reconstructed data real-space positions;
# in this case, do: data_positions_rec = recon.read_shifted_positions('data')
data_positions_rec = recon.read_shifted_positions(data_positions)
# RecSym = remove large scale RSD from randoms
randoms_positions_rec = recon.read_shifted_positions(randoms_positions)
# or RecIso
# randoms_positions_rec = recon.read_shifted_positions(randoms_positions, field='disp')

Also provided a script to run reconstruction as a standalone:

pyrecon [-h] config-fn [--data-fn [<fits, hdf5 file>]] [--randoms-fn [<fits, hdf5 file>]] [--output-data-fn [<fits, hdf5 file>]] [--output-randoms-fn [<fits, hdf5file>]]

An example of configuration file is provided in config. data-fn, randoms-fn are input data and random file names to override those in configuration file. The same holds for output files output-data-fn, output-randoms-fn.

In progress

Check algorithm details (see notes in docstrings).

Documentation

Documentation is hosted on Read the Docs, pyrecon docs.

Requirements

Only strict requirement is:

• numpy

Extra requirements are:

• pyfftw (for faster FFTs)
• fitsio, h5py, astropy to run pyrecon as a standalone
• pypower to evaluate reconstruction metrics (correlation, transfer function and propagator)

Installation

See pyrecon docs.

License

pyrecon is free software distributed under a BSD3 license. For details see the LICENSE.

Credits

• Martin J. White for https://github.com/martinjameswhite/recon_code
• Julian E. Bautista for https://github.com/julianbautista/eboss_clustering/blob/master/python/recon.py
• Pedro Rangel Caetano for inspiration for the script bin/recon
• Sesh Nadathur for careful checks against Revolver https://github.com/seshnadathur/Revolver/blob/main/python_tools/recon.py
• Enrique Paillas for bug reports
• Grant Merz for propagator https://github.com/grantmerz/DESI_Recon
• Davide Bianchi for checks of pair counts and normalization with PIP weights