HPGeom: HEALPix Geometry Routines with Python and Numpy

HPGeom is a lightweight implementation of HEALPix geometry functions, wrapped in a numpy interface. The implementation is based on the geometric functions in the original HEALPix C++ library code. This has an all-new API, but there are compatibility functions with the same interfaces as healpy for easy transition from healpy to HPGeom.

The HPGeom package addresses multiple issues in the default healpy routines.

• HPGeom is lightweight, with no plotting or i/o routines. Therefore it is fast to load with no dependencies on matplotlib or cfitsio.

• HPGeom only depends on python, numpy and a working C compiler.

The code is hosted in GitHub. Please use the issue tracker to let us know about any problems or questions with the code. The list of released versions of this package can be found here, with the main branch including the most recent (non-released) development.

The HPGeom code was written by Eli Rykoff based on HEALPix c++ code as well as work by Matt Becker and Erin Sheldon. This software was developed under the Rubin Observatory Legacy Survey of Space and Time (LSST) Dark Energy Science Collaboration (DESC) using LSST DESC resources. The DESC acknowledges ongoing support from the Institut National de Physique Nucléaire et de Physique des Particules in France; the Science & Technology Facilities Council in the United Kingdom; and the Department of Energy, the National Science Foundation, and the LSST Corporation in the United States. DESC uses resources of the IN2P3 Computing Center (CC-IN2P3–Lyon/Villeurbanne - France) funded by the Centre National de la Recherche Scientifique; the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231; STFC DiRAC HPC Facilities, funded by UK BEIS National E-infrastructure capital grants; and the UK particle physics grid, supported by the GridPP Collaboration. This work was performed in part under DOE Contract DE-AC02-76SF00515.

Contents:

• Install
• Basic HPGeom Interface
  • Getting Started
  • Key Differences Between healpy and HPGeom
  • Conversion Between Angles and Pixels
  • Pixel Queries
  • Pixel Boundaries and Neighbors
  • Healpy Compatibility Module

Modules API Reference

• hpgeom modules
  • hpgeom
    • angle_to_pixel()
    • angle_to_vector()
    • boundaries()
    • get_interpolation_weights()
    • lonlat_to_thetaphi()
    • max_pixel_radius()
    • neighbors()
    • nest_to_ring()
    • npixel_to_nside()
    • nside_to_npixel()
    • nside_to_order()
    • nside_to_pixel_area()
    • nside_to_resolution()
    • order_to_nside()
    • pixel_ranges_to_pixels()
    • pixel_to_angle()
    • pixel_to_vector()
    • query_box()
    • query_circle()
    • query_circle_vec()
    • query_ellipse()
    • query_polygon()
    • query_polygon_vec()
    • reorder()
    • ring_to_nest()
    • thetaphi_to_lonlat()
    • upgrade_pixel_ranges()
    • upgrade_pixels()
    • vector_to_angle()
    • vector_to_pixel()
  • healpy compatibility
    • ang2pix()
    • ang2vec()
    • boundaries()
    • get_all_neighbours()
    • get_interp_weights()
    • max_pixrad()
    • nest2ring()
    • npix2nside()
    • nside2npix()
    • nside2order()
    • nside2pixarea()
    • nside2resol()
    • order2nside()
    • pix2ang()
    • pix2vec()
    • query_disc()
    • query_polygon()
    • ring2nest()
    • vec2ang()
    • vec2pix()

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