def areaint(lats, lons):
assert lats.size == lons.size, 'List of latitudes and longitudes are different sizes.'
if isinstance(lats.iloc[0], u.Quantity):
lat = np.array([lat.value
for lat in lats] + [lats.iloc[0].value]) * u.deg
lon = np.array([lon.value
for lon in lons] + [lons.iloc[0].value]) * u.deg
else:
lat = np.append(lats, lats.iloc[0]) * u.deg
lon = np.append(lons, lons.iloc[0]) * u.deg
if lat.max() > 0:
northern = True
# Get colatitude (a measure of surface distance as an angle) and
# azimuth of each point in segment from the center of mass.
_, center_lat, center_lon = sph_center_of_mass(lat[:-1], lon[:-1])
if np.isnan(center_lat.value):
center_lat = Latitude(0, unit=u.rad)
if np.isnan(center_lon.value):
center_lon = Longitude(0, unit=u.rad)
# force centroid at the N or S pole
# if northern:
# center_lat = 90 * u.deg
# else:
# center_lat = -90 * u.deg
# center_lon = 0 * u.deg
colat = np.array([
distance(center_lon.to(u.deg), center_lat.to(u.deg), longi, latit).to(
u.deg).value for latit, longi in zip(lat, lon)
]) * u.deg
az = np.array([
azimuth(center_lon.to(u.deg), center_lat.to(u.deg), longi, latit).to(
u.deg).value for latit, longi in zip(lat, lon)
]) * u.deg
# Calculate step sizes, taking the complementary angle where needed
daz = np.diff(az).to(u.rad)
daz[np.where(daz > 180 * u.deg)] -= 360. * u.deg
daz[np.where(daz < -180 * u.deg)] += 360. * u.deg
# Determine average surface distance for each step
deltas = np.diff(colat) / 2.
colats = colat[0:-1] + deltas
# Integral over azimuth is 1-cos(colatitudes)
integrands = (1 - np.cos(colats)) * daz
# Integrate and return the answer as a fraction of the unit sphere.
# Note that the sum of the integrands will include a part of 4pi.
return np.abs(
np.nansum(integrands)) / (4 * np.pi * u.rad), center_lat, center_lon
def location(lat, lon, alt):
# Reference location
lon = Longitude(lon.strip(),
u.degree,
wrap_angle=180 * u.degree,
copy=False) # noqa
lat = Latitude(lat.strip(), u.degree, copy=False)
height = u.Quantity(float(alt.strip()), u.m, copy=False)
ref_location = EarthLocation(lat=lat.to(u.deg).value,
lon=lon.to(u.deg).value,
height=height.to(u.m).value) # noqa
return ref_location
def pixel_to_data(self, x, y, origin=0):
"""
Convert a pixel coordinate to a data (world) coordinate by using
`~astropy.wcs.WCS.wcs_pix2world`.
Parameters
----------
x : float
Pixel coordinate of the CTYPE1 axis. (Normally solar-x).
y : float
Pixel coordinate of the CTYPE2 axis. (Normally solar-y).
origin : int
Origin of the top-left corner. i.e. count from 0 or 1.
Normally, origin should be 0 when passing numpy indices, or 1 if
passing values from FITS header or map attributes.
See `~astropy.wcs.WCS.wcs_pix2world` for more information.
Returns
-------
x : `~astropy.units.Quantity`
Coordinate of the CTYPE1 axis. (Normally solar-x).
y : `~astropy.units.Quantity`
Coordinate of the CTYPE2 axis. (Normally solar-y).
"""
x, y = self.wcs.wcs_pix2world(x, y, origin)
# If the wcs is celestial it is output in degress
if self.wcs.is_celestial:
x *= u.deg
y *= u.deg
else:
x *= self.units.x
y *= self.units.y
x = Longitude(x, wrap_angle=180 * u.deg)
y = Latitude(y)
return x.to(self.units.x), y.to(self.units.y)