def save_grib2(cube, target, append=False, **kwargs):
"""
Save a cube to a GRIB2 file.
Args:
* cube - A :class:`iris.cube.Cube`, :class:`iris.cube.CubeList` or list of cubes.
* target - A filename or open file handle.
Kwargs:
* append - Whether to start a new file afresh or add the cube(s) to the end of the file.
Only applicable when target is a filename, not a file handle.
Default is False.
See also :func:`iris.io.save`.
"""
# grib file (this bit is common to the pp and grib savers...)
if isinstance(target, basestring):
grib_file = open(target, "ab" if append else "wb")
elif hasattr(target, "write"):
if hasattr(target, "mode") and "b" not in target.mode:
raise ValueError("Target not binary")
grib_file = target
else:
raise ValueError("Can only save grib to filename or writable")
# discover the lat and lon coords (this bit is common to the pp and grib savers...)
lat_coords = filter(lambda coord: "latitude" in coord.name(), cube.coords())
lon_coords = filter(lambda coord: "longitude" in coord.name(), cube.coords())
if len(lat_coords) != 1 or len(lon_coords) != 1:
raise TranslationError("Did not find one (and only one) "
"latitude or longitude coord")
# Save each latlon slice2D in the cube
for slice2D in cube.slices([lat_coords[0], lon_coords[0]]):
# Save this slice to the grib file
grib_message = gribapi.grib_new_from_samples("GRIB2")
_save_rules.run(slice2D, grib_message)
gribapi.grib_write(grib_message, grib_file)
gribapi.grib_release(grib_message)
# (this bit is common to the pp and grib savers...)
if isinstance(target, basestring):
grib_file.close()
def as_pairs(cube):
"""
Convert one or more cubes to (2D cube, GRIB message) pairs.
Returns an iterable of tuples each consisting of one 2D cube and
one GRIB message ID, the result of the 2D cube being processed by the GRIB
save rules.
Args:
* cube - A :class:`iris.cube.Cube`, :class:`iris.cube.CubeList` or
list of cubes.
"""
x_coords = cube.coords(axis='x', dim_coords=True)
y_coords = cube.coords(axis='y', dim_coords=True)
if len(x_coords) != 1 or len(y_coords) != 1:
raise TranslationError("Did not find one (and only one) x or y coord")
# Save each latlon slice2D in the cube
for slice2D in cube.slices([y_coords[0], x_coords[0]]):
grib_message = gribapi.grib_new_from_samples("GRIB2")
_save_rules.run(slice2D, grib_message)
yield (slice2D, grib_message)
def as_pairs(cube):
"""
Convert one or more cubes to (2D cube, GRIB message) pairs.
Returns an iterable of tuples each consisting of one 2D cube and
one GRIB message ID, the result of the 2D cube being processed by the GRIB
save rules.
Args:
* cube - A :class:`iris.cube.Cube`, :class:`iris.cube.CubeList` or
list of cubes.
"""
x_coords = cube.coords(axis='x', dim_coords=True)
y_coords = cube.coords(axis='y', dim_coords=True)
if len(x_coords) != 1 or len(y_coords) != 1:
raise TranslationError("Did not find one (and only one) x or y coord")
# Save each latlon slice2D in the cube
for slice2D in cube.slices([y_coords[0], x_coords[0]]):
grib_message = gribapi.grib_new_from_samples("GRIB2")
_save_rules.run(slice2D, grib_message)
yield (slice2D, grib_message)