"""

Plugin for reading ECHAM-HAM NetCDF output files.

"""

def _create_cube(self, filenames, variable):

"""Creates a cube for the specified variable.

:param filenames: List of filenames to read coordinates from

:param variable: Optional variable to read while we're reading the coordinates, can be a string or a

VariableConstraint object

:return: If variable was specified this will return an UngriddedData object, otherwise a CoordList

"""

from cis.exceptions import InvalidVariableError

from cis.data_io import gridded_data

import iris

# Check if the files given actually exist.

for filename in filenames:

with open(filename) as f:

pass

variable_constraint = variable

if isinstance(variable, str):

variable_constraint = DisplayConstraint(cube_func=(lambda c: c.var_name == variable or

c.standard_name == variable or

c.long_name == variable), display=variable,

coord_values={'hybrid level at layer midpoints':

(lambda lev: lev == 31)})

if len(filenames) == 1:

callback_function = self.load_single_file_callback

else:

callback_function = self.load_multiple_files_callback

try:

cube = gridded_data.load_cube(filenames, variable_constraint, callback=callback_function)

except iris.exceptions.ConstraintMismatchError as e:

if variable is None:

message = "File contains more than one cube variable name must be specified"

elif e.message == "no cubes found":

message = "Variable not found: {} \nTo see a list of variables run: cis info {}" \

.format(str(variable), filenames[0])

else:

message = e.message

raise InvalidVariableError(message)

except ValueError as e:

raise IOError(str(e))

self._add_available_aux_coords(cube, filenames)