Source code for improver.utilities.time_lagging

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"""Provide support utilities for time lagging ensembles"""

from typing import List, Union

import numpy as np
from iris.cube import Cube, CubeList

from improver import BasePlugin
from improver.metadata.forecast_times import rebadge_forecasts_as_latest_cycle
from improver.utilities.cube_manipulation import MergeCubes


[docs]class GenerateTimeLaggedEnsemble(BasePlugin): """Combine realizations from different forecast cycles into one cube"""
[docs] def process(self, cubelist: Union[List[Cube], CubeList]) -> Cube: """ Take an input cubelist containing forecasts from different cycles and merges them into a single cube. The steps taken are: 1. Update forecast reference time and period to match the latest contributing cycle. 2. Check for duplicate realization numbers. If a duplicate is found, renumber all of the realizations uniquely. 3. Concatenate into one cube along the realization axis. Args: cubelist: List of input forecasts Returns: Concatenated forecasts """ cubelist = rebadge_forecasts_as_latest_cycle(cubelist) # 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 realizations 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, dtype=np.int32 ) first_realization = first_realization + n_realization # slice over realization to deal with cases where direct concatenation # would result in a non-monotonic coordinate lagged_ensemble = MergeCubes()(cubelist, slice_over_realization=True) return lagged_ensemble