improver.ensemble_copula_coupling.utilities module
This module defines the utilities required for Ensemble Copula Coupling plugins.
- choose_set_of_percentiles(no_of_percentiles, sampling='quantile')[source]
Function to create percentiles.
- Parameters
no_of_percentiles (
int) – Number of percentiles.sampling (
str) –Type of sampling of the distribution to produce a set of percentiles e.g. quantile or random.
Accepted options for sampling are:
- Quantile: A regular set of equally-spaced percentiles aimed
at dividing a Cumulative Distribution Function into blocks of equal probability.
Random: A random set of ordered percentiles.
- Return type
- Returns
Percentiles calculated using the sampling technique specified.
- Raises
ValueError – if the sampling option is not one of the accepted options.
References
For further details, Flowerdew, J., 2014. Calibrating ensemble reliability whilst preserving spatial structure. Tellus, Series A: Dynamic Meteorology and Oceanography, 66(1), pp.1-20. Schefzik, R., Thorarinsdottir, T.L. & Gneiting, T., 2013. Uncertainty Quantification in Complex Simulation Models Using Ensemble Copula Coupling. Statistical Science, 28(4), pp.616-640.
- concatenate_2d_array_with_2d_array_endpoints(array_2d, low_endpoint, high_endpoint)[source]
For a 2d array, add a 2d array as the lower and upper endpoints. The concatenation to add the lower and upper endpoints to the 2d array are performed along the second (index 1) dimension.
- Parameters
- Return type
- Returns
2d array of values after padding with the low_endpoint and high_endpoint.
- create_cube_with_percentiles(percentiles, template_cube, cube_data, cube_unit=None)[source]
Create a cube with a percentile coordinate based on a template cube. The resulting cube will have an extra percentile coordinate compared with the template cube. The shape of the cube_data should be the shape of the desired output cube.
- Parameters
percentiles (
Union[List[float],ndarray]) – Ensemble percentiles. There should be the same number of percentiles as the first dimension of cube_data.template_cube (
Cube) – Cube to copy metadata from.cube_data (
ndarray) – Data to insert into the template cube. The shape of the cube_data, excluding the dimension associated with the percentile coordinate, should be the same as the shape of template_cube. For example, template_cube shape is (3, 3, 3), whilst the cube_data is (10, 3, 3, 3), where there are 10 percentiles.cube_unit (
Union[Unit,str,None]) – The units of the data within the cube, if different from those of the template_cube.
- Return type
- Returns
Cube containing a percentile coordinate as the leading dimension (or scalar percentile coordinate if single-valued)
- get_bounds_of_distribution(bounds_pairing_key, desired_units)[source]
Gets the bounds of the distribution and converts the units of the bounds_pairing to the desired_units.
This method gets the bounds values and units from the imported dictionaries: BOUNDS_FOR_ECDF and units_of_BOUNDS_FOR_ECDF. The units of the bounds are converted to be the desired units.
- Parameters
- Return type
- Returns
Lower and upper bound to be used as the ends of the empirical cumulative distribution function, converted to have the desired units.
- Raises
KeyError – If the bounds_pairing_key is not within the BOUNDS_FOR_ECDF dictionary.
- insert_lower_and_upper_endpoint_to_1d_array(array_1d, low_endpoint, high_endpoint)[source]
For a 1d array, add a lower and upper endpoint.
- interpolate_multiple_rows_same_x(*args)[source]
For each row i of fp, do the equivalent of np.interp(x, xp, fp[i, :]).
Calls a fast numba implementation where numba is available (see improver.ensemble_copula_coupling.numba_utilities.fast_interp_same_y) and calls a the native python implementation otherwise (see
slow_interp_same_y()).- Parameters
x – 1-D array
xp – 1-D array, sorted in non-decreasing order
fp – 2-D array with len(xp) columns
- Returns
- 2-D array with shape (len(fp), len(x)), with each row i equal to
np.interp(x, xp, fp[i, :])
- interpolate_multiple_rows_same_y(*args)[source]
For each row i of xp, do the equivalent of np.interp(x, xp[i], fp).
Calls a fast numba implementation where numba is available (see improver.ensemble_copula_coupling.numba_utilities.fast_interp_same_y) and calls a the native python implementation otherwise (see
slow_interp_same_y()).- Parameters
x – 1-d array
xp – n * m array, each row must be in non-decreasing order
fp – 1-d array with length m
- Returns
n * len(x) array where each row i is equal to np.interp(x, xp[i], fp)
- restore_non_percentile_dimensions(array_to_reshape, original_cube, n_percentiles)[source]
Reshape a 2d array, so that it has the dimensions of the original cube, whilst ensuring that the probabilistic dimension is the first dimension.
- Parameters
array_to_reshape (
ndarray) – The array that requires reshaping. This has dimensions “percentiles” by “points”, where “points” is a flattened array of all the other original dimensions that needs reshaping.original_cube (
Cube) – Cube slice containing the desired shape to be reshaped to, apart from the probabilistic dimension. This would typically be expected to be either [time, y, x] or [y, x].n_percentiles (
int) – Length of the required probabilistic dimension (“percentiles”).
- Return type
- Returns
The array after reshaping.
- Raises
ValueError – If the probabilistic dimension is not the first on the original_cube.
CoordinateNotFoundError – If the input_probabilistic_dimension_name is not a coordinate on the original_cube.
- slow_interp_same_x(x, xp, fp)[source]
For each row i of fp, calculate np.interp(x, xp, fp[i, :]). :type x:
ndarray:param x: 1-D array :type xp:ndarray:param xp: 1-D array, sorted in non-decreasing order :type fp:ndarray:param fp: 2-D array with len(xp) columns- Return type
- Returns
- 2-D array with shape (len(fp), len(x)), with each row i equal to
np.interp(x, xp, fp[i, :])