1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
"""
===============================================
How to create an GWCS from quantities and times
===============================================
This example shows how to create a GWCS from astropy quantities.
"""
import numpy as np
from matplotlib import pyplot as plt
import astropy.units as u
from astropy.time import Time
from ndcube import NDCube
from ndcube.extra_coords import QuantityTableCoordinate, TimeTableCoordinate
##############################################################################
# We aim to create coordinates that are focused around time and energies using astropy quantities.
energy = np.arange(10) * u.keV
time = Time('2020-01-01 00:00:00') + np.arange(9)*u.s
##############################################################################
# Then, we need to turn these into lookup tables using
# `~ndcube.extra_coords.table_coord.QuantityTableCoordinate` and
# `~ndcube.extra_coords.table_coord.TimeTableCoordinate` to create table coordinates.
energy_coord = QuantityTableCoordinate(energy, names='energy', physical_types='em.energy')
print(energy_coord)
time_coord = TimeTableCoordinate(time, names='time', physical_types='time')
print(time_coord)
##############################################################################
# Now we need to combine table coordinates created above and extract the ``.wcs`` from the result.
wcs = (time_coord & energy_coord).wcs
print(wcs)
##############################################################################
# Now, we have all the pieces required to construct a `~ndcube.NDCube` with this data and the GWCS we just created.
data = np.random.rand(len(time), len(energy))
cube = NDCube(data=data, wcs=wcs)
print(cube)
##############################################################################
# Finally, we will plot the cube.
cube.plot()
plt.show()
|
