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"""Provide support utilities for time lagging ensembles"""
import numpy as np
from improver.utilities.temporal import (
unify_forecast_reference_time, cycletime_to_datetime,
find_latest_cycletime)
from improver.utilities.cube_manipulation import merge_cubes
[docs]class GenerateTimeLaggedEnsemble(object):
"""
A plugin to combine realizations from different forecast cycles into one
cube.
"""
[docs] def __init__(self, cycletime=None):
"""
Initialise class.
Keyword Args:
cycletime (str):
A string of form YYYYMMDDTHHMMZ describing the
forecast_reference_time we want the resulting cube to be
relative to. Default None in which case the latest
forecast_reference_time from the input cubes is used.
"""
self.cycletime = cycletime
def __repr__(self):
"""Represent the configured plugin instance as a string."""
result = ('<GenerateTimeLaggedEnsemble: cycletime: {}>')
return result.format(self.cycletime)
[docs] def process(self, cubelist):
"""
Take an input cubelist containing forecasts from different cycles and
merges them into a single cube.
The steps taken are:
1. If no cycletime is given then find the latest cycle time from
the input cubes.
2. Update the forecast periods in each input cube to be relative
to the new cycletime.
3. Checks if there are duplicate realization numbers. If a
duplicate is found, renumbers all of the realizations to remove
any duplicates.
4. Merge cubes into one cube, removing any metadata that
doesn't match.
"""
if self.cycletime is None:
cycletime = find_latest_cycletime(cubelist)
else:
cycletime = cycletime_to_datetime(self.cycletime)
cubelist = unify_forecast_reference_time(cubelist, cycletime)
# Take all the realizations from all the input cube and
# put in one array
all_realizations = [
cube.coord("realization").points for cube in cubelist]
all_realizations = np.concatenate(all_realizations)
# Find unique realiations
unique_realizations = np.unique(all_realizations)
# If we have fewer unique realizations than total realizations we have
# duplicate realizations so we rebadge all realizations in the cubelist
if len(unique_realizations) < len(all_realizations):
first_realization = 0
for cube in cubelist:
n_realization = len(cube.coord("realization").points)
cube.coord("realization").points = np.arange(
first_realization, first_realization + n_realization)
first_realization = first_realization + n_realization
lagged_ensemble = merge_cubes(cubelist)
return lagged_ensemble