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import math
import numpy as np
import matplotlib.pyplot as plt
class BaseGrid(object):
_valid_grid_types = ['RectGrid', 'HexGrid']
_valid_mixed_types = ['MixedGrid']
class Grid(BaseGrid):
def __init__(self, grid_spacing, wcs, Npix_x=10000, Npix_y=10000, pixelscale=0.074, rot_angle=None, pos_offset=None, angle_unit='rad'):
self.grid_spacing = grid_spacing
self.im_gs = grid_spacing * (1.0 / pixelscale) # pixels
self.pixelscale = pixelscale
self.Npix_x, self.Npix_y = Npix_x, Npix_y
self.wcs = wcs
self.rot_angle = rot_angle # rotation angle, in rad
self.angle_unit = angle_unit
if pos_offset:
self.pos_offset = np.array(pos_offset)
else:
self.pos_offset = np.array([0., 0.])
# May have to modify grid corners if there is a rotation
if rot_angle:
dx = Npix_x / 2.
dy = Npix_y / 2.
if angle_unit == 'deg':
theta = np.deg2rad(rot_angle)
else:
theta = rot_angle
self.startx = (0.-dx) * np.cos(theta) - (Npix_y-dy) * np.sin(theta) + dx
self.endx = (Npix_x-dx) * np.cos(theta) - (0.-dy) * np.sin(theta) + dx
self.starty = (0.-dx) * np.cos(theta) + (0.-dy) * np.sin(theta) + dx
self.endy = (Npix_x-dx) * np.cos(theta) + (Npix_y-dy) * np.sin(theta) + dx
else:
self.startx, self.endx= 0., Npix_x
self.starty, self.endy= 0., Npix_y
def rotate_grid(self, theta, offset=None, angle_unit='rad'):
if angle_unit == 'deg':
theta = np.deg2rad(theta)
elif angle_unit != 'rad':
raise ValueError('`angle_unit` can only be `deg` or `rad`! ' +
'Passed unit of {}'.format(angle_unit))
if not offset: offset = [0., 0.]
c, s = np.cos(theta), np.sin(theta)
R = np.array(((c,-s), (s, c)))
offset_grid = np.array([self.im_ra - offset[0], self.im_dec - offset[1]])
translate = np.empty_like(offset_grid)
translate[0,:] = offset[0]
translate[1,:] = offset[1]
rotated_grid = np.dot(R, offset_grid) + translate
self.im_pos = rotated_grid.T
self.im_ra, self.im_dec = self.im_pos[0,:], self.im_pos[1,:]
def cut2buffer(self):
'''
Remove objects outside of tile (and buffer).
We must sample points in the buffer zone in the beginning due to
possible rotations.
'''
b = self.im_gs
in_region = np.where( (self.im_pos[:,0]>b) & (self.im_pos[:,0]<self.Npix_x-b) &
(self.im_pos[:,1]>b) & (self.im_pos[:,1]<self.Npix_y-b) )
self.im_pos = self.im_pos[in_region]
self.im_ra = self.im_pos[:,0]
self.im_dec = self.im_pos[:,1]
# Get all image coordinate pairs
self.pos = self.wcs.wcs_pix2world(self.im_pos, 1)
self.ra = self.pos[:,0]
self.dec = self.pos[:,1]
class RectGrid(Grid):
def __init__(self, grid_spacing, wcs, Npix_x=10000, Npix_y=10000, pixelscale=0.074,
rot_angle=None, pos_offset=None, angle_unit='rad'):
super(RectGrid, self).__init__(grid_spacing, wcs, Npix_x=Npix_x, Npix_y=Npix_y,
pixelscale=pixelscale, rot_angle=rot_angle,
pos_offset=pos_offset, angle_unit=angle_unit)
self._create_grid()
def _create_grid(self):
im_gs = self.im_gs
po = self.pos_offset
im_po = po / self.pixelscale
self.im_ra = np.arange(self.startx, self.endx, im_gs)
self.im_dec = np.arange(self.starty, self.endy, im_gs)
# Get all image coordinate pairs
self.im_pos = np.array(np.meshgrid(self.im_ra, self.im_dec)).T.reshape(
-1, 2)
self.im_ra = self.im_pos[:,0]
self.im_dec = self.im_pos[:,1]
if self.rot_angle:
self.rotate_grid(self.rot_angle, angle_unit=self.angle_unit,
offset=[(self.Npix_x+im_po[0])/2., (self.Npix_y+im_po[1])/2.])
self.cut2buffer()
class HexGrid(Grid):
def __init__(self, grid_spacing, wcs, Npix_x=10000, Npix_y=10000, pixelscale=0.074,
rot_angle=None, pos_offset=None, angle_unit='rad'):
super(HexGrid, self).__init__(grid_spacing, wcs, Npix_x=Npix_x, Npix_y=Npix_y,
pixelscale=pixelscale, rot_angle=rot_angle,
pos_offset=pos_offset, angle_unit=angle_unit)
self._create_grid()
def _create_grid(self):
im_gs = self.im_gs
po = self.pos_offset
im_po = [p / self.pixelscale for p in po]
self.im_pos = HexGrid.calc_hex_coords(self.startx, self.starty, self.endx, self.endy, im_gs)
self.im_ra = self.im_pos[:, 0]
self.im_dec = self.im_pos[:, 1]
if self.rot_angle:
self.rotate_grid(self.rot_angle, angle_unit=self.angle_unit,
offset=[(self.Npix_x+im_po[0])/2., (self.Npix_y+im_po[1])/2.])
self.cut2buffer()
@classmethod
def calc_hex_coords(cls, startx, starty, endx, endy, radius):
# Geoemtric factors of given hexagon
r = radius
p = r * np.tan(np.pi / 6.) # side length / 2
h = 4. * p
dx = 2. * r
dy = 2. * p
row = 1
xs = []
ys = []
while startx < endx:
x = [startx, startx, startx + r, startx + dx, startx + dx, startx + r, startx + r]
xs.append(x)
startx += dx
while starty < endy:
y = [starty + p, starty + 3*p, starty + h, starty + 3*p, starty + p, starty, starty + dy]
ys.append(y)
starty += 2*p
row += 1
print(xs)
print(ys)
polygons = [zip(x, y) for x in xs for y in ys]
polygons = [np.column_stack((x, y)) for x in xs for y in ys]
# polygons = np.array(polygons)
hexgrid = cls.polygons2coords(polygons)
# Some hexagonal elements go beyond boundary; cut these out
indx = np.where( (hexgrid[:,0]<endx) & (hexgrid[:,1]<endy) )
return hexgrid[indx]
@classmethod
def polygons2coords(HexGrid, p):
print(p)
s = np.shape(p)
print(s)
L = s[0]*s[1]
pp = np.array(p).reshape(L,2)
c = np.vstack({tuple(row) for row in pp})
# Some of the redundant coordinates are offset by ~1e-10 pixels
return np.unique(c.round(decimals=6), axis=0)
def _build_grid(grid_type, **kwargs):
if grid_type in GRID_TYPES:
return GRID_TYPES[grid_type](**kwargs)
else:
raise ValueError('There is not yet an implemnted default Grid of type {}'.format(grid_type))
GRID_TYPES = {
'RectGrid': RectGrid,
'HexGrid': HexGrid
}