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| -rwxr-xr-x | astro/21cm/extract_slice.py | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/astro/21cm/extract_slice.py b/astro/21cm/extract_slice.py new file mode 100755 index 0000000..576b7ee --- /dev/null +++ b/astro/21cm/extract_slice.py @@ -0,0 +1,84 @@ +#!/usr/bin/env python3 +# +# Copyright (c) 2017 Weitian LI <weitian@aaronly.me> +# MIT License +# + +""" +Extract a slice from the 21cm cube and save as FITS image. +""" + +import os +import sys +import argparse + +import numpy as np +import astropy.io.fits as fits + + +def main(): + outfile_default = "{prefix}_z{z:05.2f}_N{Nside}_L{Lside}_s{sidx}.fits" + + parser = argparse.ArgumentParser( + description="Extract a slice from cube and save as FITS image") + parser.add_argument("-C", "--clobber", dest="clobber", + action="store_true", + help="overwrite existing files") + parser.add_argument("-d", "--dtype", dest="dtype", default="float32", + help="NumPy dtype of data cubes (default: float32)") + parser.add_argument("-z", "--redshift", dest="redshift", + type=float, required=True, + help="redshift of the input data cube") + parser.add_argument("-L", "--len-side", dest="Lside", + type=float, required=True, + help="Side length of the cube [comoving Mpc]") + parser.add_argument("-s", "--slice-idx", dest="sidx", + type=int, default=None, + help="slice index to be extracted (default: " + "the central slice)") + parser.add_argument("-u", "--unit", dest="unit", + help="data unit (e.g., K, mK)") + parser.add_argument("-i", "--infile", dest="infile", required=True, + help="input data cube") + parser.add_argument("-o", "--outfile", dest="outfile", + default=outfile_default, + help="output FITS image slice (default: %s)" % + outfile_default) + parser.add_argument("-p", "--prefix", dest="prefix", required=True, + help="prefix for the output FITS image") + args = parser.parse_args() + + cube = np.fromfile(open(args.infile, "rb"), dtype=args.dtype) + Nside = round(cube.shape[0] ** (1.0/3)) + print("Read cube: %s (Nside=%d)" % (args.infile, Nside)) + if args.sidx is None: + sidx = int(Nside / 2.0) + elif args.idx >= 0 and args.idx < Nside: + sidx = args.idx + else: + raise ValueError("invalid slice index: %s" % args.sidx) + outfile = args.outfile.format(prefix=args.prefix, z=args.redshift, + Nside=Nside, Lside=args.Lside, sidx=sidx) + if os.path.exists(outfile) and not args.clobber: + raise OSError("output file already exists: %s" % outfile) + + cube = cube.reshape((Nside, Nside, Nside)) + simg = cube[:, :, sidx] + header = fits.Header() + header["REDSHIFT"] = args.redshift + header["Lside"] = (args.Lside, "Cube side length [comoving Mpc]") + header["Nside"] = (Nside, "Number of pixels on each cube side") + header["SliceIdx"] = (sidx, "Index of this extracted slice") + if args.unit: + header["BUNIT"] = (args.unit, "Data unit") + header.add_history(" ".join(sys.argv)) + hdu = fits.PrimaryHDU(data=simg, header=header) + try: + hdu.writeto(outfile, overwrite=args.clobber) + except TypeError: + hdu.writeto(outfile, clobber=args.clobber) + print("Extracted #%d slice: %s" % (sidx, outfile)) + + +if __name__ == "__main__": + main() |