HipsTile¶

class hips.HipsTile(meta: hips.tiles.tile.HipsTileMeta, raw_data: bytes) → None[source]¶

Bases: object

HiPS tile container.

This class provides methods for fetching, reading, and writing a HiPS tile.

Note

In HiPS, the pixel data is flipped in the y direction for jpg and png format with respect to FITS. In this package, we handle this by flipping jpg and png data to match the fits orientation, at the I/O boundary, i.e. in from_numpy and to_numpy.

Parameters:

meta : HipsTileMeta

Metadata of HiPS tile

raw_data : bytes

Raw data (copy of bytes from file)

Examples

Fetch a HiPS tile:

>>> from hips import HipsTile, HipsTileMeta
>>> meta = HipsTileMeta(order=6, ipix=30889, file_format='fits')
>>> url = 'http://alasky.unistra.fr/2MASS/H/Norder6/Dir30000/Npix30889.fits'
>>> tile = HipsTile.fetch(meta, url)

The tile pixel data is available as a Numpy array:

>>> type(tile.data)
numpy.ndarray
>>> tile.data.shape
(512, 512)
>>> tile.data.dtype.name
int16

Attributes Summary

`children`	Create four children tiles from parent tile.
`data`	Tile pixel data (`ndarray`).

Methods Summary

`fetch`((meta: hips.tiles.tile.HipsTileMeta, …)	Fetch HiPS tile and load into memory (`HipsTile`).
`from_numpy`(…)	Create a tile from given pixel data.
`read`((meta: hips.tiles.tile.HipsTileMeta, …)	Read HiPS tile data from a directory and load into memory (`HipsTile`).
`to_numpy`((raw_data: bytes, …)	Convert raw image bytes to Numpy array pixel data.
`write`((filename: str) -> None)	Write to file.

Attributes Documentation

children¶: Create four children tiles from parent tile.

data¶

Tile pixel data (ndarray).

This is a cached property, it will only be computed once.

See the to_numpy function.

Methods Documentation

classmethod fetch(meta: hips.tiles.tile.HipsTileMeta, url: str) → hips.tiles.tile.HipsTile[source]¶

Fetch HiPS tile and load into memory (HipsTile).

Parameters:

meta : HipsTileMeta

Metadata of HiPS tile

url : str

URL containing HiPS tile

classmethod from_numpy(meta: hips.tiles.tile.HipsTileMeta, data: numpy.ndarray) → hips.tiles.tile.HipsTile[source]¶

Create a tile from given pixel data.

Parameters:

meta : HipsTileMeta

Metadata of HiPS tile

data : ndarray

Tile pixel data

Returns:

tile : HipsTile

HiPS tile object in the format requested in meta.

classmethod read(meta: hips.tiles.tile.HipsTileMeta, filename: str = None) → hips.tiles.tile.HipsTile[source]¶

Read HiPS tile data from a directory and load into memory (HipsTile).

Parameters:

meta : HipsTileMeta

Metadata of HiPS tile

filename : str

Filename

static to_numpy(raw_data: bytes, fmt: str) → numpy.ndarray[source]¶

Convert raw image bytes to Numpy array pixel data.

Parameters:

raw_data : bytes

Raw image bytes (usually read from file or fetched from URL)

fmt : {‘fits’, ‘jpg’, ‘png’}

File format

Returns:

data : ndarray

Pixel data as a numpy array

write(filename: str) → None[source]¶

Write to file.

Parameters:

filename : str

Filename