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"""Module for loading cubes."""
import glob
import iris
from improver.utilities.cube_manipulation import (
enforce_coordinate_ordering, merge_cubes)
[docs]def load_cube(filepath, constraints=None, no_lazy_load=False,
allow_none=False):
"""Load the filepath provided using Iris into a cube.
Args:
filepath (str or list):
Filepath that will be loaded or list of filepaths that can be
merged into a single cube upon loading.
constraints (iris.Constraint, str or None):
Constraint to be applied when loading from the input filepath.
This can be in the form of an iris.Constraint or could be a string
that is intended to match the name of the cube.
The default is None.
no_lazy_load (bool):
If True, bypass cube deferred (lazy) loading and load the whole
cube into memory. This can increase performance at the cost of
memory. If False (default) then lazy load.
allow_none (bool):
If True, when the filepath is None, returns None.
If False, normal error handling applies.
Default is False.
Returns:
iris.cube.Cube:
Cube that has been loaded from the input filepath given the
constraints provided.
"""
if filepath is None and allow_none:
return None
# Remove metadata prefix cube if present
constraints = iris.Constraint(
cube_func=lambda cube: cube.long_name != 'prefixes') & constraints
# Load each file individually to avoid partial merging (not used
# iris.load_raw() due to issues with time representation)
if isinstance(filepath, str):
cubes = iris.load(filepath, constraints=constraints)
else:
cubes = iris.cube.CubeList([])
for item in filepath:
cubes.extend(iris.load(item, constraints=constraints))
# Merge loaded cubes
if not cubes:
message = "No cubes found using contraints {}".format(constraints)
raise ValueError(message)
if len(cubes) == 1:
cube = cubes[0]
else:
cube = merge_cubes(cubes)
# Remove metadata prefix cube attributes
if 'bald__isPrefixedBy' in cube.attributes.keys():
cube.attributes.pop('bald__isPrefixedBy')
# Ensure the probabilistic coordinates are the first coordinates within a
# cube and are in the specified order.
enforce_coordinate_ordering(
cube, ["realization", "percentile", "threshold"])
# Ensure the y and x dimensions are the last dimensions within the cube.
y_name = cube.coord(axis="y").name()
x_name = cube.coord(axis="x").name()
enforce_coordinate_ordering(
cube, [y_name, x_name], anchor_start=False)
if no_lazy_load:
# Force the cube's data into memory by touching the .data attribute.
cube.data
return cube
[docs]def load_cubelist(filepath, constraints=None, no_lazy_load=False):
"""Load one cube from each of the filepath(s) provided using Iris into
a cubelist.
Args:
filepath (str or list):
Filepath(s) that will be loaded, each containing a single cube. If
wildcarded, this will be expanded into a list of file names so that
only one cube is loaded per file.
constraints (iris.Constraint, str or None):
Constraint to be applied when loading from the input filepath.
This can be in the form of an iris.Constraint or could be a string
that is intended to match the name of the cube.
The default is None.
no_lazy_load (bool)
If True, bypass cube deferred (lazy) loading and load the whole
cube into memory. This can increase performance at the cost of
memory. If False (default) then lazy load.
Returns:
iris.cube.CubeList:
CubeList that has been created from the input filepath given the
constraints provided.
"""
if isinstance(filepath, list) and len(filepath) == 1:
filepath = filepath[0]
# If the filepath is a string, then use glob, in case the str contains
# wildcards.
if isinstance(filepath, str):
filepaths = glob.glob(filepath)
else:
filepaths = filepath
# Construct a cubelist using the load_cube function.
cubelist = iris.cube.CubeList([])
for filepath in filepaths:
try:
cube = load_cube(filepath, constraints=constraints)
except ValueError:
continue
if no_lazy_load:
# Force the cube's data into memory by touching the .data.
cube.data
cubelist.append(cube)
return cubelist