1 files changed, 69 insertions, 0 deletions
diff --git a/bin/hpx2healpix b/bin/hpx2healpix
new file mode 100755
index 0000000..6f83426
--- /dev/null
+++ b/bin/hpx2healpix
@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) 2016 Weitian LI <liweitianux@live.com>
+# MIT license
+
+"""
+Recover the sky map in HPX projection format back into HEALPix table format,
+i.e., the reverse of `healpix2hpx.py`.
+"""
+
+import os
+import sys
+import argparse
+
+import numpy as np
+from astropy.io import fits
+
+import fg21sim
+from fg21sim.utils import hpx2healpix
+
+
+# Reference:
+# http://docs.astropy.org/en/stable/io/fits/usage/table.html#column-creation
+FITS_COLUMN_FORMATS = {
+    np.dtype("int16"): "I",
+    np.dtype("int32"): "J",
+    np.dtype("int64"): "K",
+    np.dtype("float32"): "E",
+    np.dtype("float64"): "D",
+}
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Recover the image in HPX projection to HEALPix data")
+    parser.add_argument("infile", help="input FITS image in HPX projection")
+    parser.add_argument("outfile", help="output HEALPix data file")
+    parser.add_argument("-C", "--clobber", action="store_true",
+                        help="overwrite the existing output file")
+    parser.add_argument("-F", "--float", action="store_true",
+                        help="use float (single precision) instead of double")
+    args = parser.parse_args()
+
+    tool = os.path.basename(sys.argv[0])
+    history = [
+        "TOOL: {0}".format(tool),
+        "PARAM: {0}".format(" ".join(sys.argv[1:])),
+    ]
+    comments = [
+        'Tool "{0}" is part of the "{1}" package'.format(tool,
+                                                         fg21sim.__title__),
+        'distributed under {0} license.'.format(fg21sim.__license__),
+        'See also {0}'.format(fg21sim.__url__)
+    ]
+
+    hp_data, hp_header = hpx2healpix(args.infile,
+                                     append_history=history,
+                                     append_comment=comments)
+    if args.float:
+        hp_data = hp_data.astype(np.float32)
+    hdu = fits.BinTableHDU.from_columns([
+        fits.Column(name="I", array=hp_data,
+                    format=FITS_COLUMN_FORMATS.get(hp_data.dtype))
+    ], header=hp_header)
+    hdu.writeto(args.outfile, clobber=args.clobber, checksum=True)
+
+
+if __name__ == "__main__":
+    main()