def _add_forecast_reference_time(input_time: Coord, advected_cube: Cube) -> None:
"""Add or replace a forecast reference time on the advected cube"""
try:
advected_cube.remove_coord("forecast_reference_time")
except CoordinateNotFoundError:
pass
frt_coord_name = "forecast_reference_time"
frt_coord_spec = TIME_COORDS[frt_coord_name]
frt_coord = input_time.copy()
frt_coord.rename(frt_coord_name)
frt_coord.convert_units(frt_coord_spec.units)
frt_coord.points = round_close(frt_coord.points, dtype=frt_coord_spec.dtype)
advected_cube.add_aux_coord(frt_coord)
def pad_coord(coord: Coord, width: int, method: str) -> Coord:
"""
Construct a new coordinate by extending the current coordinate by the
padding width.
Args:
coord:
Original coordinate which will be used as the basis of the
new extended coordinate.
width:
The width of padding in grid cells (the extent of the
neighbourhood radius in grid cells in a given direction).
method:
A string determining whether the coordinate is being expanded
or contracted. Options: 'remove' to remove points from coord;
'add' to add points to coord.
Returns:
Coordinate with expanded or contracted length, to be added to
the padded or unpadded iris cube.
Raises:
ValueError: Raise an error if non-uniform increments exist between
grid points.
"""
orig_points = coord.points
increment = orig_points[1:] - orig_points[:-1]
if np.isclose(np.sum(np.diff(increment)), 0):
increment = increment[0]
else:
msg = "Non-uniform increments between grid points: " "{}.".format(
increment)
raise ValueError(msg)
if method == "add":
num_of_new_points = len(orig_points) + width + width
new_points = np.linspace(
orig_points[0] - width * increment,
orig_points[-1] + width * increment,
num_of_new_points,
dtype=np.float32,
)
elif method == "remove":
end_width = -width if width != 0 else None
new_points = np.float32(orig_points[width:end_width])
new_points = new_points.astype(orig_points.dtype)
new_points_bounds = np.array(
[new_points - 0.5 * increment, new_points + 0.5 * increment],
dtype=np.float32).T
return coord.copy(points=new_points, bounds=new_points_bounds)
def iris_time_to_datetime(time_coord: Coord,
point_or_bound: str = "point") -> List[datetime]:
"""
Convert iris time to python datetime object. Working in UTC.
Args:
time_coord:
Iris time coordinate element(s).
Returns:
The time element(s) recast as a python datetime object.
"""
coord = time_coord.copy()
coord.convert_units("seconds since 1970-01-01 00:00:00")
if point_or_bound == "point":
datetime_list = [value.point for value in coord.cells()]
elif point_or_bound == "bound":
datetime_list = [value.bound for value in coord.cells()]
return datetime_list
def grid_spacing(coord: Coord) -> float:
"""Calculate grid spacing along a given spatial axis"""
new_coord = coord.copy()
new_coord.convert_units("m")
return np.float32(np.diff((new_coord).points)[0])
