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# Copyright (c) 2017 Weitian LI <weitian@aaronly.me>
# MIT license
"""
Generic simulation sky supporting both sky patch and HEALPix all-sky
maps.
"""
import os
import logging
import copy
from scipy import ndimage
from astropy.io import fits
import astropy.units as au
import healpy as hp
from .utils.fits import read_fits_healpix, write_fits_healpix
logger = logging.getLogger(__name__)
class SkyPatch:
"""
Support reading & writing FITS file of sky patches.
Parameters
----------
size : (xsize, ysize) tuple
The (pixel) dimensions of the (output) sky patch.
If the input sky has a different size, then it will be *scaled*
to match this output size.
NOTE: Due to the FITS using Fortran ordering, while Python/numpy
using C ordering, therefore, the read in image/data array
has shape (ysize, xsize).
pixelsize : float
The pixel size of the sky patch, will be used to determine
the sky coordinates. [ arcmin ]
center : (ra, dec) tuple
The (R.A., Dec.) coordinate of the sky patch center. [ deg ]
infile : str
The path to the input sky patch
Attributes
----------
size : int tuple, (width, height)
The dimensions of the FITS image
shape : int tuple, (nrow, ncol)
The shape of the Numpy array
NOTE: nrow=height, ncol=width
pixelsize : float
The pixel size of the sky map [ arcmin ]
center : float tuple, (ra, dec)
The (R.A., Dec.) coordinate of the sky patch center. [ deg ]
"""
type_ = "patch"
# Input sky patch and its frequency [ MHz ]
infile = None
frequency = None
# Sky data; should be a ``numpy.ndarray``
data = None
# Coordinates of each pixel
coordinates = None
def __init__(self, size, pixelsize, center=(0.0, 0.0),
infile=None, frequency=None):
self.xcenter, self.ycenter = center
self.xsize, self.ysize = size
self.pixelsize = pixelsize
if infile is not None:
self.read(infile, frequency)
@property
def size(self):
return (self.xsize, self.ysize)
@property
def shape(self):
if self.data is not None:
return self.data.shape
else:
return (self.ysize, self.xsize)
@property
def center(self):
return (self.xcenter, self.ycenter)
def read(self, infile, frequency=None):
"""
Read input sky data from file.
Parameters
----------
infile : str
The path to the input sky patch
frequency : float, optional
The frequency of the sky patch; [ MHz ]
"""
self.infile = infile
if frequency is not None:
self.frequency = frequency * au.MHz
with fits.open(infile) as f:
self.data = f[0].data
self.header = f[0].header
self.ysize_in, self.xsize_in = self.data.shape
logger.info("Read sky patch from: %s (%dx%d)" %
(infile, self.xsize_in, self.ysize_in))
if (self.xsize_in != self.xsize) or (self.ysize_in != self.ysize):
logger.warning("Scale input sky patch from size " +
"%dx%d to %dx%d" % (self.xsize_in, self.ysize_in,
self.xsize, self.ysize))
self.data = ndimage.zoom(self.data, order=1,
zoom=(self.ysize/self.ysize_in,
self.xsize/self.xsize_in))
def load(self, infile, frequency=None):
"""
Make a new copy of this instance, then read the input sky patch
and return the loaded new instance.
Returns
-------
A new copy of this instance with the given sky patch loaded.
"""
sky = self.copy()
sky.read(infile=infile, frequency=frequency)
return sky
def copy(self):
"""
Return a copy of this instance.
"""
return copy.deepcopy(self)
def write(self, outfile, clobber=False, checksum=True):
"""
Write current data to file.
"""
outdir = os.path.dirname(outfile)
if not os.path.exists(outdir):
os.makedirs(outdir)
logger.info("Created output directory: %s" % outdir)
hdu = fits.PrimaryHDU(data=self.data, header=self.header)
hdu.writeto(outfile, clobber=clobber, checksum=checksum)
logger.info("Write sky map to file: %s" % outfile)
class SkyHealpix:
"""
Support the HEALPix all-sky map.
Parameters
----------
nside : int
The pixel resolution of HEALPix (must be power of 2)
Attributes
----------
shape : int tuple, (npix,)
The shape of the Numpy array
NOTE: nrow=height, ncol=width
pixelsize : float
The pixel size of the HEALPix sky [ arcmin ]
"""
type_ = "healpix"
# Input sky patch and its frequency [ MHz ]
infile = None
frequency = None
# Sky data; should be a ``numpy.ndarray``
data = None
# Coordinates of each pixel
coordinates = None
def __init__(self, nside, infile=None, frequency=None):
self.nside = nside
if infile is not None:
self.read(infile, frequency)
@property
def shape(self):
if self.data is not None:
return self.data.shape
else:
return (hp.nside2npix(self.nside), )
@property
def pixelsize(self):
return hp.nside2resol(self.nside, arcmin=True)
def read(self, infile, frequency=None):
"""
Read input HEALPix all-sky map.
Parameters
----------
infile : str
The path to the input HEALPix all-sky map.
frequency : float, optional
The frequency of the sky patch; [ MHz ]
"""
self.infile = infile
if frequency is not None:
self.frequency = frequency * au.MHz
self.data, self.header = read_fits_healpix(infile)
self.nside_in = self.header["NSIDE"]
logger.info("Read HEALPix sky map from: {0} (Nside={1})".format(
infile, self.nside_in))
if self.nside_in != self.nside:
self.data = hp.ud_grade(self.data, nside_out=self.nside)
logger.warning("Upgrade/downgrade sky map from Nside " +
"{0} to {1}".format(self.nside_in, self.nside))
def load(self, infile, frequency=None):
"""
Make a new copy of this instance, then read the input sky map
and return the loaded new instance.
Returns
-------
A new copy of this instance with the given sky map loaded.
"""
sky = self.copy()
sky.read(infile=infile, frequency=frequency)
return sky
def copy(self):
"""
Return a copy of this instance.
"""
return copy.deepcopy(self)
def write(self, outfile, clobber=False, checksum=True):
"""
Write current data to file.
"""
outdir = os.path.dirname(outfile)
if not os.path.exists(outdir):
os.makedirs(outdir)
logger.info("Created output directory: %s" % outdir)
write_fits_healpix(outfile, self.data, header=self.header,
clobber=clobber, checksum=checksum)
logger.info("Write sky map to file: %s" % outfile)
def get_sky(configs):
"""
Sky class factory function to support both the sky patch and
HEALPix all-sky map.
Parameters
----------
configs : ConfigManager object
An `ConfigManager` object contains default and user configurations.
For more details, see the example config specification.
"""
skytype = configs.getn("sky/type")
if skytype == "patch":
sec = "sky/patch"
xsize = configs.getn(sec+"/xsize")
ysize = configs.getn(sec+"/ysize")
xcenter = configs.getn(sec+"/xcenter")
ycenter = configs.getn(sec+"/ycenter")
pixelsize = configs.getn(sec+"/pixelsize")
return SkyPatch(size=(xsize, ysize), pixelsize=pixelsize,
center=(xcenter, ycenter))
elif skytype == "healpix":
sec = "sky/healpix"
nside = configs.getn(sec+"/nside")
return SkyHealpix(nside=nside)
else:
raise ValueError("unknown sky type: %s" % skytype)
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