# healpy.pixelfunc.get_all_neighbours¶

healpy.pixelfunc.get_all_neighbours(nside, theta, phi=None, nest=False, lonlat=False)

Return the 8 nearest pixels.

Parameters
nsideint

the nside to work with

theta, phiscalar or array-like

if phi is not given or None, theta is interpreted as pixel number, otherwise, theta[rad],phi[rad] are angular coordinates

nestbool

if True, pixel number will be NESTED ordering, otherwise RING ordering.

lonlatbool

If True, input angles are assumed to be longitude and latitude in degree, otherwise, they are co-latitude and longitude in radians.

Returns
ipixint, array

pixel number of the SW, W, NW, N, NE, E, SE and S neighbours, shape is (8,) if input is scalar, otherwise shape is (8, N) if input is of length N. If a neighbor does not exist (it can be the case for W, N, E and S) the corresponding pixel number will be -1.

Examples

>>> import healpy as hp
>>> print(hp.get_all_neighbours(1, 4))
[11  7  3 -1  0  5  8 -1]

>>> print(hp.get_all_neighbours(1, np.pi/2, np.pi/2))
[ 8  4  0 -1  1  6  9 -1]

>>> print(hp.get_all_neighbours(1, 90, 0, lonlat=True))
[ 8  4  0 -1  1  6  9 -1]