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Allow passing None for all coord-system optional args.
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@pp-mo
pp-mo committed Sep 8, 2020
1 parent 37f4106 commit 57a53ac
Showing 1 changed file with 106 additions and 71 deletions.
177 changes: 106 additions & 71 deletions lib/iris/coord_systems.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,15 @@
import cartopy.crs as ccrs


def _arg_default(value, default, as_type=float):
"""Apply a default value and type for an optional kwarg."""
if value is None:
value = default
if as_type is not None:
value = as_type(value)
return value


class CoordSystem(metaclass=ABCMeta):
"""
Abstract base class for coordinate systems.
Expand Down Expand Up @@ -107,7 +116,7 @@ def __init__(
semi_major_axis=None,
semi_minor_axis=None,
inverse_flattening=None,
longitude_of_prime_meridian=0,
longitude_of_prime_meridian=None,
):
"""
Creates a new GeogCS.
Expand Down Expand Up @@ -208,7 +217,9 @@ def __init__(
self.inverse_flattening = float(inverse_flattening)

#: Describes 'zero' on the ellipsoid in degrees.
self.longitude_of_prime_meridian = float(longitude_of_prime_meridian)
self.longitude_of_prime_meridian = _arg_default(
longitude_of_prime_meridian, 0
)

def _pretty_attrs(self):
attrs = [("semi_major_axis", self.semi_major_axis)]
Expand Down Expand Up @@ -285,7 +296,7 @@ def __init__(
self,
grid_north_pole_latitude,
grid_north_pole_longitude,
north_pole_grid_longitude=0,
north_pole_grid_longitude=None,
ellipsoid=None,
):
"""
Expand Down Expand Up @@ -320,7 +331,9 @@ def __init__(
self.grid_north_pole_longitude = float(grid_north_pole_longitude)

#: Longitude of true north pole in rotated grid in degrees.
self.north_pole_grid_longitude = float(north_pole_grid_longitude)
self.north_pole_grid_longitude = _arg_default(
north_pole_grid_longitude, 0
)

#: Ellipsoid definition.
self.ellipsoid = ellipsoid
Expand Down Expand Up @@ -397,9 +410,9 @@ def __init__(
self,
latitude_of_projection_origin,
longitude_of_central_meridian,
false_easting,
false_northing,
scale_factor_at_central_meridian,
false_easting=None,
false_northing=None,
scale_factor_at_central_meridian=None,
ellipsoid=None,
):
"""
Expand All @@ -413,18 +426,21 @@ def __init__(
* longitude_of_central_meridian
True longitude of planar origin in degrees.
Kwargs:
* false_easting
X offset from planar origin in metres.
Defaults to 0.
* false_northing
Y offset from planar origin in metres.
Defaults to 0.
* scale_factor_at_central_meridian
Reduces the cylinder to slice through the ellipsoid
(secant form). Used to provide TWO longitudes of zero
distortion in the area of interest.
Kwargs:
Defaults to 1.0.
* ellipsoid
Optional :class:`GeogCS` defining the ellipsoid.
Expand All @@ -447,14 +463,14 @@ def __init__(
)

#: X offset from planar origin in metres.
self.false_easting = float(false_easting)
self.false_easting = _arg_default(false_easting, 0)

#: Y offset from planar origin in metres.
self.false_northing = float(false_northing)
self.false_northing = _arg_default(false_northing, 0)

#: Reduces the cylinder to slice through the ellipsoid (secant form).
self.scale_factor_at_central_meridian = float(
scale_factor_at_central_meridian
self.scale_factor_at_central_meridian = _arg_default(
scale_factor_at_central_meridian, 1.0
)

#: Ellipsoid definition.
Expand Down Expand Up @@ -524,8 +540,8 @@ def __init__(
self,
latitude_of_projection_origin,
longitude_of_projection_origin,
false_easting=0.0,
false_northing=0.0,
false_easting=None,
false_northing=None,
ellipsoid=None,
):
"""
Expand Down Expand Up @@ -562,10 +578,10 @@ def __init__(
)

#: X offset from planar origin in metres.
self.false_easting = float(false_easting)
self.false_easting = _arg_default(false_easting, 0)

#: Y offset from planar origin in metres.
self.false_northing = float(false_northing)
self.false_northing = _arg_default(false_northing, 0)

#: Ellipsoid definition.
self.ellipsoid = ellipsoid
Expand Down Expand Up @@ -615,8 +631,8 @@ def __init__(
latitude_of_projection_origin,
longitude_of_projection_origin,
perspective_point_height,
false_easting=0,
false_northing=0,
false_easting=None,
false_northing=None,
ellipsoid=None,
):
"""
Expand Down Expand Up @@ -661,10 +677,10 @@ def __init__(
self.perspective_point_height = float(perspective_point_height)

#: X offset from planar origin in metres.
self.false_easting = float(false_easting)
self.false_easting = _arg_default(false_easting, 0)

#: Y offset from planar origin in metres.
self.false_northing = float(false_northing)
self.false_northing = _arg_default(false_northing, 0)

#: Ellipsoid definition.
self.ellipsoid = ellipsoid
Expand Down Expand Up @@ -769,14 +785,10 @@ def __init__(
self.perspective_point_height = float(perspective_point_height)

#: X offset from planar origin in metres.
if false_easting is None:
false_easting = 0
self.false_easting = float(false_easting)
self.false_easting = _arg_default(false_easting, 0)

#: Y offset from planar origin in metres.
if false_northing is None:
false_northing = 0
self.false_northing = float(false_northing)
self.false_northing = _arg_default(false_northing, 0)

#: The axis along which the satellite instrument sweeps - 'x' or 'y'.
self.sweep_angle_axis = sweep_angle_axis
Expand Down Expand Up @@ -831,8 +843,8 @@ def __init__(
self,
central_lat,
central_lon,
false_easting=0.0,
false_northing=0.0,
false_easting=None,
false_northing=None,
true_scale_lat=None,
ellipsoid=None,
):
Expand Down Expand Up @@ -870,10 +882,10 @@ def __init__(
self.central_lon = float(central_lon)

#: X offset from planar origin in metres.
self.false_easting = float(false_easting)
self.false_easting = _arg_default(false_easting, 0)

#: Y offset from planar origin in metres.
self.false_northing = float(false_northing)
self.false_northing = _arg_default(false_northing, 0)

#: Latitude of true scale.
self.true_scale_lat = float(true_scale_lat) if true_scale_lat else None
Expand Down Expand Up @@ -922,11 +934,11 @@ class LambertConformal(CoordSystem):

def __init__(
self,
central_lat=39.0,
central_lon=-96.0,
false_easting=0.0,
false_northing=0.0,
secant_latitudes=(33, 45),
central_lat=None,
central_lon=None,
false_easting=None,
false_northing=None,
secant_latitudes=None,
ellipsoid=None,
):
"""
Expand All @@ -935,19 +947,20 @@ def __init__(
Kwargs:
* central_lat
The latitude of "unitary scale".
The latitude of "unitary scale". Defaults to 39.0
* central_lon
The central longitude.
The central longitude. Defaults to -96.0
* false_easting
X offset from planar origin in metres.
X offset from planar origin in metres. Defaults to 0
* false_northing
Y offset from planar origin in metres.
Y offset from planar origin in metres. Defaults to 0
* secant_latitudes
Latitudes of secant intersection.
Latitudes of secant intersection. One or two.
Defaults to (33.0, 45.0)
* ellipsoid
:class:`GeogCS` defining the ellipsoid.
Expand All @@ -962,18 +975,22 @@ def __init__(
"""

#: True latitude of planar origin in degrees.
self.central_lat = central_lat
self.central_lat = _arg_default(central_lat, 39.0)
#: True longitude of planar origin in degrees.
self.central_lon = central_lon
self.central_lon = _arg_default(central_lon, -96.0)
#: X offset from planar origin in metres.
self.false_easting = false_easting
self.false_easting = _arg_default(false_easting, 0)
#: Y offset from planar origin in metres.
self.false_northing = false_northing
#: The one or two standard parallels of the cone.
self.false_northing = _arg_default(false_northing, 0)
secant_latitudes = _arg_default(
secant_latitudes, (33, 45), as_type=None
)
try:
self.secant_latitudes = tuple(secant_latitudes)
secant_latitudes = tuple(secant_latitudes)
except TypeError:
self.secant_latitudes = (secant_latitudes,)
secant_latitudes = (secant_latitudes,)
#: The one or two standard parallels of the cone.
self.secant_latitudes = tuple(float(x) for x in secant_latitudes)
nlats = len(self.secant_latitudes)
if nlats == 0 or nlats > 2:
emsg = "Either one or two secant latitudes required, got {}"
Expand Down Expand Up @@ -1032,28 +1049,30 @@ class Mercator(CoordSystem):

def __init__(
self,
longitude_of_projection_origin=0.0,
longitude_of_projection_origin=None,
ellipsoid=None,
standard_parallel=0.0,
standard_parallel=None,
):
"""
Constructs a Mercator coord system.
Kwargs:
* longitude_of_projection_origin
True longitude of planar origin in degrees.
True longitude of planar origin in degrees. Defaults to 0
* ellipsoid
:class:`GeogCS` defining the ellipsoid.
* standard_parallel
the latitude where the scale is 1. Defaults to 0 degrees.
"""
#: True longitude of planar origin in degrees.
self.longitude_of_projection_origin = longitude_of_projection_origin
self.longitude_of_projection_origin = _arg_default(
longitude_of_projection_origin, 0
)
#: Ellipsoid definition.
self.ellipsoid = ellipsoid
#: The latitude where the scale is 1 (defaults to 0 degrees).
self.standard_parallel = standard_parallel
self.standard_parallel = _arg_default(standard_parallel, 0)

def __repr__(self):
res = (
Expand Down Expand Up @@ -1087,10 +1106,10 @@ class LambertAzimuthalEqualArea(CoordSystem):

def __init__(
self,
latitude_of_projection_origin=0.0,
longitude_of_projection_origin=0.0,
false_easting=0.0,
false_northing=0.0,
latitude_of_projection_origin=None,
longitude_of_projection_origin=None,
false_easting=None,
false_northing=None,
ellipsoid=None,
):
"""
Expand All @@ -1115,13 +1134,17 @@ def __init__(
"""
#: True latitude of planar origin in degrees.
self.latitude_of_projection_origin = latitude_of_projection_origin
self.latitude_of_projection_origin = _arg_default(
latitude_of_projection_origin, 0
)
#: True longitude of planar origin in degrees.
self.longitude_of_projection_origin = longitude_of_projection_origin
self.longitude_of_projection_origin = _arg_default(
longitude_of_projection_origin, 0
)
#: X offset from planar origin in metres.
self.false_easting = false_easting
self.false_easting = _arg_default(false_easting, 0)
#: Y offset from planar origin in metres.
self.false_northing = false_northing
self.false_northing = _arg_default(false_northing, 0)
#: Ellipsoid definition.
self.ellipsoid = ellipsoid

Expand Down Expand Up @@ -1163,11 +1186,11 @@ class AlbersEqualArea(CoordSystem):

def __init__(
self,
latitude_of_projection_origin=0.0,
longitude_of_central_meridian=0.0,
false_easting=0.0,
false_northing=0.0,
standard_parallels=(20.0, 50.0),
latitude_of_projection_origin=None,
longitude_of_central_meridian=None,
false_easting=None,
false_northing=None,
standard_parallels=None,
ellipsoid=None,
):
"""
Expand Down Expand Up @@ -1197,15 +1220,27 @@ def __init__(
"""
#: True latitude of planar origin in degrees.
self.latitude_of_projection_origin = latitude_of_projection_origin
self.latitude_of_projection_origin = _arg_default(
latitude_of_projection_origin, 0
)
#: True longitude of planar central meridian in degrees.
self.longitude_of_central_meridian = longitude_of_central_meridian
self.longitude_of_central_meridian = _arg_default(
longitude_of_central_meridian, 0
)
#: X offset from planar origin in metres.
self.false_easting = false_easting
self.false_easting = _arg_default(false_easting, 0)
#: Y offset from planar origin in metres.
self.false_northing = false_northing
self.false_northing = _arg_default(false_northing, 0)

standard_parallels = _arg_default(
standard_parallels, (20, 50), as_type=None
)
try:
standard_parallels = tuple(standard_parallels)
except TypeError:
standard_parallels = (standard_parallels,)
#: The one or two latitudes of correct scale.
self.standard_parallels = standard_parallels
self.standard_parallels = tuple(float(x) for x in standard_parallels)
#: Ellipsoid definition.
self.ellipsoid = ellipsoid

Expand Down

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