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]
```