API reference

This page contains the complete documentation of all the functions and classes available in healpix-geo.

Overview

healpix-geo is organised in several modules following the HEALPix indexing scheme used :

• Module nested : nested scheme

• Module ring : ring scheme

• Module zuniq : Zuniq scheme for Multi-Order Coverage (MOC)

• Module auto: indexing scheme-agnostic API

Tip

For most of the applications, use module healpix_geo.auto with the nested indexing scheme. It offers the best support for hierarchical operations.

Helpers

geometry.Bbox(lon_min, lat_min, lon_max, lat_max)	bounding box
slices.Slice(start, stop[, step])	More powerful version of the built-in slice
slices.ConcreteSlice()	Slice with concrete values
slices.MultiConcreteSlice()	Multiple concrete positional slices

Common Parameters

healpix-geo functions shares common parameters :

Geographical coordinates

• lon (array-like) : Longitude(s) in degrees [-180, 180]

• lat (array-like) : Latitude(s) in degrees [-90, 90]

HEALPix indices

• ipix (array-like of int) : Indice(s) of HEALPix cell

• depth (int) : resolution level [0, 29]

  • 0 = coarser (12 cells)

  • 29 = finer (~1.2 cm)

  • See Cell statistics for the complete table

Ellipsoids

• ellipsoid (str) : Ellipsoidal Model to use

  • "WGS84" : Standard GPS

  • "GRS80" : Geodesic System of reference 1980

  • "WGS72" : Old standard GPS

  • "sphere" : Perfect sphere

Tip

Always use ellipsoid="WGS84" for real geospatial applications. See Ellipsoids basics for more details.

Conventions

Return types

• Functions returns numpy arrays

• Coordinates are always in decimal degrees

• Indices are always unsigned integers (uint64)

Vectorisation

All functions are vectorized and accept:

• Scalars (automatically converted to arrays)

• 1D NumPy arrays

• Multidimensional NumPy arrays (depending on the function)