def _slice_from_path(x, y, data, attribute, slc):
"""
Extract a PV-like slice from a cube
:param x: An array of x values to extract (pixel units)
:param y: An array of y values to extract (pixel units)
:param data: :class:`~glue.core.data.Data`
:param attribute: :claass:`~glue.core.data.Component`
:param slc: orientation of the image widget that `pts` are defined on
:returns: (slice, x, y)
slice is a 2D Numpy array, corresponding to a "PV ribbon"
cutout from the cube
x and y are the resampled points along which the
ribbon is extracted
:note: For >3D cubes, the "V-axis" of the PV slice is the longest
cube axis ignoring the x/y axes of `slc`
"""
from glue.external.pvextractor import Path, extract_pv_slice
p = Path(list(zip(x, y)))
cube = data[attribute]
dims = list(range(data.ndim))
s = list(slc)
ind = _slice_index(data, slc)
cube_wcs = getattr(data.coords, 'wcs', None)
# transpose cube to (z, y, x, <whatever>)
def _swap(x, s, i, j):
x[i], x[j] = x[j], x[i]
s[i], s[j] = s[j], s[i]
_swap(dims, s, ind, 0)
_swap(dims, s, s.index('y'), 1)
_swap(dims, s, s.index('x'), 2)
cube = cube.transpose(dims)
# slice down from >3D to 3D if needed
s = [slice(None)] * 3 + [slc[d] for d in dims[3:]]
cube = cube[s]
# sample cube
spacing = 1 # pixel
x, y = [np.round(_x).astype(int) for _x in p.sample_points(spacing)]
try:
result = extract_pv_slice(cube, path=p, wcs=cube_wcs, order=0)
except: # sometimes pvextractor complains due to wcs. Try to recover
result = extract_pv_slice(cube, path=p, wcs=None, order=0)
from astropy.wcs import WCS
data = result.data
wcs = WCS(result.header)
return data, x, y, wcs
def _slice_from_path(x, y, data, attribute, slc):
"""
Extract a PV-like slice from a cube
:param x: An array of x values to extract (pixel units)
:param y: An array of y values to extract (pixel units)
:param data: :class:`~glue.core.data.Data`
:param attribute: :claass:`~glue.core.data.Component`
:param slc: orientation of the image widget that `pts` are defined on
:returns: (slice, x, y)
slice is a 2D Numpy array, corresponding to a "PV ribbon"
cutout from the cube
x and y are the resampled points along which the
ribbon is extracted
:note: For >3D cubes, the "V-axis" of the PV slice is the longest
cube axis ignoring the x/y axes of `slc`
"""
from glue.external.pvextractor import Path, extract_pv_slice
p = Path(list(zip(x, y)))
cube = data[attribute]
dims = list(range(data.ndim))
s = list(slc)
ind = _slice_index(data, slc)
cube_wcs = getattr(data.coords, 'wcs', None)
# transpose cube to (z, y, x, <whatever>)
def _swap(x, s, i, j):
x[i], x[j] = x[j], x[i]
s[i], s[j] = s[j], s[i]
_swap(dims, s, ind, 0)
_swap(dims, s, s.index('y'), 1)
_swap(dims, s, s.index('x'), 2)
cube = cube.transpose(dims)
# slice down from >3D to 3D if needed
s = [slice(None)] * 3 + [slc[d] for d in dims[3:]]
cube = cube[s]
# sample cube
spacing = 1 # pixel
x, y = [np.round(_x).astype(int) for _x in p.sample_points(spacing)]
try:
result = extract_pv_slice(cube, path=p, wcs=cube_wcs, order=0)
except: # sometimes pvextractor complains due to wcs. Try to recover
result = extract_pv_slice(cube, path=p, wcs=None, order=0)
from astropy.wcs import WCS
data = result.data
wcs = WCS(result.header)
return data, x, y, wcs