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Diffstat (limited to 'fg21sim/utils/fits.py')
-rw-r--r-- | fg21sim/utils/fits.py | 152 |
1 files changed, 0 insertions, 152 deletions
diff --git a/fg21sim/utils/fits.py b/fg21sim/utils/fits.py deleted file mode 100644 index 4991cd0..0000000 --- a/fg21sim/utils/fits.py +++ /dev/null @@ -1,152 +0,0 @@ -# Copyright (c) 2016 Weitian LI <liweitianux@live.com> -# MIT license - -""" -FITS utilities --------------- - -read_fits_healpix: - Read the HEALPix map from a FITS file or a BinTableHDU to 1D array - in *RING* ordering. - -write_fits_healpix: - Write the HEALPix map to a FITS file with proper header as well - as the user-provided header. -""" - -from datetime import datetime, timezone - -import numpy as np -from astropy.io import fits -import healpy as hp - - -# Column formats for FITS binary table -# Reference: -# http://docs.astropy.org/en/stable/io/fits/usage/table.html#column-creation -FITS_COLUMN_FORMATS = { - np.dtype("bool"): "L", - np.dtype("uint8"): "B", - np.dtype("int16"): "I", - np.dtype("int32"): "J", - np.dtype("int64"): "K", - np.dtype("float32"): "E", - np.dtype("float64"): "D", - np.dtype("complex64"): "C", - np.dtype("complex128"): "M", -} - - -def read_fits_healpix(filename): - """Read the HEALPix map from a FITS file or a BinTableHDU to 1D array - in *RING* ordering. - - Parameters - ---------- - filename : str or `~astropy.io.fits.BinTableHDU` - Filename of the HEALPix FITS file, - or an `~astropy.io.fits.BinTableHDU` instance. - - Returns - ------- - data : 1D `~numpy.ndarray` - HEALPix data in *RING* ordering with same dtype as input - header : `~astropy.io.fits.Header` - Header of the input FITS file - - NOTE - ---- - This function wraps on `healpy.read_map()`, but set the data type of - data array to its original value as in FITS file, as well as return - FITS header as `~astropy.io.fits.Header` instance. - """ - if isinstance(filename, fits.BinTableHDU): - hdu = filename - else: - # Read the first extended table - hdu = fits.open(filename)[1] - # Hack to ignore the dtype byteorder, use native endianness - dtype = np.dtype(hdu.data.field(0).dtype.type) - header = hdu.header - data = hp.read_map(hdu, nest=False, verbose=False) - return (data.astype(dtype), header) - - -def write_fits_healpix(filename, hpmap, header=None, clobber=False, - checksum=False): - """Write the HEALPix map to a FITS file with proper header as well - as the user-provided header. - - This function currently only support one style of HEALPix with the - following specification: - - Only one column: I (intensity) - - ORDERING: RING - - COORDSYS: G (Galactic) - - OBJECT: FULLSKY - - INDXSCHM: IMPLICIT - - Parameters - ---------- - filename : str - Filename of the output file to write the HEALPix map data - hpmap : 1D `~numpy.ndarray` - 1D array containing the HEALPix map data, and the ordering - scheme should be "RING"; - The data type is preserved in the output FITS file. - header : `~astropy.io.fits.Header`, optional - Extra header to be appended to the output FITS - clobber : bool, optional - Whether overwrite the existing file? - checksum : bool, optional - Whether calculate the checksum for the output file, which is - recorded as the "CHECKSUM" header keyword. - - NOTE - ---- - - This function is intended to replace the most common case of - `healpy.write_map()`, which still uses some deprecated functions of - `numpy` and `astropy`, meanwhile, it interface/arguments is not very - handy. - - This function (currently) only implement the very basic feature of - the `healpy.write_map()`. - """ - hpmap = np.asarray(hpmap) - if hpmap.ndim != 1: - raise ValueError("Invalid HEALPix data: only support 1D array") - # Hack to ignore the dtype byteorder, use native endianness - dtype = np.dtype(hpmap.dtype.type) - hpmap = hpmap.astype(dtype) - # - npix = hpmap.size - nside = int((npix / 12) ** 0.5) - colfmt = FITS_COLUMN_FORMATS.get(hpmap.dtype) - if hpmap.size > 1024: - hpmap = hpmap.reshape(int(hpmap.size/1024), 1024) - colfmt = "1024" + colfmt - # - hdr = fits.Header() - # set HEALPix parameters - hdr["PIXTYPE"] = ("HEALPIX", "HEALPix pixelization") - hdr["ORDERING"] = ("RING", - "Pixel ordering scheme, either RING or NESTED") - hdr["COORDSYS"] = ("G", "Ecliptic, Galactic or Celestial (equatorial)") - hdr["NSIDE"] = (nside, "HEALPix resolution parameter") - hdr["NPIX"] = (npix, "Total number of pixels") - hdr["FIRSTPIX"] = (0, "First pixel # (0 based)") - hdr["LASTPIX"] = (npix-1, "Last pixel # (0 based)") - hdr["INDXSCHM"] = ("IMPLICIT", "Indexing: IMPLICIT or EXPLICIT") - hdr["OBJECT"] = ("FULLSKY", "Sky coverage, either FULLSKY or PARTIAL") - # - hdr["EXTNAME"] = ("HEALPIX", "Name of the binary table extension") - hdr["CREATOR"] = (__name__, "File creator") - hdr["DATE"] = (datetime.now(timezone.utc).astimezone().isoformat(), - "File creation date") - # Merge user-provided header - # NOTE: use the `.extend()` method instead of `.update()` method - if header is not None: - hdr.extend(fits.Header(header)) - # - hdu = fits.BinTableHDU.from_columns([ - fits.Column(name="I", array=hpmap, format=colfmt) - ], header=hdr) - hdu.writeto(filename, clobber=clobber, checksum=checksum) |