API

This is the API for the cdshealpix Python package.

This package is a wrapper around the Rust cdshealpix crate. The functions currently implemented by cdshealpix are the following:

cdshealpix

The HEALPix cells can be represented following two schema. The nested and the ring one.

Here are two methods in the cdshealpix base module allowing to convert HEALPix cells represented in the nested scheme into cells represented in the ring scheme and vice versa.

to_ring(ipix, depth[, num_threads])	Convert HEALPix cells from the NESTED to the RING scheme.
from_ring(ipix, depth[, num_threads])	Convert HEALPix cells from the RING to the NESTED scheme.

cdshealpix.nested

The HEALPix cells at \(depth=1\) represented in the nested scheme

lonlat_to_healpix(lon, lat, depth[, ...])	Get the HEALPix indexes that contains specific sky coordinates.
skycoord_to_healpix(skycoord, depth[, ...])	Get the HEALPix indexes that contains specific sky coordinates.
healpix_to_lonlat(ipix, depth[, dx, dy, ...])	Get the longitudes and latitudes of the center of some HEALPix cells at a given depth.
healpix_to_skycoord(ipix, depth[, dx, dy, ...])	Get the sky coordinates of the center of some HEALPix cells in a nested configuration at a given depth.
healpix_to_xy(ipix, depth[, num_threads])	Project the center of a HEALPix cell to the xy-HEALPix plane.
lonlat_to_xy(lon, lat[, num_threads])	Project sky coordinates to the HEALPix space.
xy_to_lonlat(x, y[, num_threads])	Project coordinates from the HEALPix space to the sky coordinate space.
vertices(ipix, depth[, step, num_threads])	Get the longitudes and latitudes of the vertices of some HEALPix cells at a given depth.
vertices_skycoord(ipix, depth[, step, ...])	Get the sky coordinates of the vertices of some HEALPix cells at a given depth.
neighbours(ipix, depth[, num_threads])	Get the neighbouring cells of some HEALPix cells at a given depth.
external_neighbours(ipix, depth, delta_depth)	Get the neighbours of specific healpix cells.
cone_search(lon, lat, radius, depth[, ...])	Get the HEALPix cells contained in a cone at a given depth.
polygon_search(lon, lat, depth[, flat])	Get the HEALPix cells contained in a polygon at a given depth.
elliptical_cone_search(lon, lat, a, b, pa, depth)	Get the HEALPix cells contained in an elliptical cone at a given depth.
bilinear_interpolation(lon, lat, depth[, ...])	Compute the HEALPix bilinear interpolation from sky coordinates.

cdshealpix.ring

The ring scheme HEALPix methods take a nside parameter instead of a depth one. nside refers to the number of cells being contained in the side of a base cell (i.e. the 12 cells at the depth 0). While in the nested scheme, nside is a power of two (because \(N_{side} = 2 ^ {depth}\)), in the ring scheme, nside does not necessary have to be a power of two!

The HEALPix cells at \(N_{side}=2\) represented in the ring scheme

lonlat_to_healpix(lon, lat, nside[, ...])	Get the HEALPix indexes that contains specific sky coordinates.
skycoord_to_healpix(skycoord, nside[, ...])	Get the HEALPix indexes that contains specific sky coordinates.
healpix_to_lonlat(ipix, nside[, dx, dy, ...])	Get the longitudes and latitudes of the center of some HEALPix cells at a given depth.
healpix_to_skycoord(ipix, nside[, dx, dy, ...])	Get the sky coordinates of the center of some HEALPix cells at a given nside.
healpix_to_xy(ipix, nside[, num_threads])	Project the center of a HEALPix cell to the xy-HEALPix plane.
vertices(ipix, nside[, step, num_threads])	Get the longitudes and latitudes of the vertices of some HEALPix cells at a given nside.
vertices_skycoord(ipix, nside[, step])	Get the sky coordinates of the vertices of some HEALPix cells at a given nside.