improver.utilities.mathematical_operations module

Module to contain mathematical operations.

class improver.utilities.mathematical_operations.Integration(coord_name_to_integrate, start_point=None, end_point=None, direction_of_integration='negative')[source]

Bases: improver.BasePlugin

Perform integration along a chosen coordinate. This class currently supports the integration of positive values only, in order to support its usage as part of computing the wet-bulb temperature integral. Generalisation of this class to support standard numerical integration can be undertaken, if required.

__init__(coord_name_to_integrate, start_point=None, end_point=None, direction_of_integration='negative')[source]

Initialise class.

Parameters

  • coord_name_to_integrate (str) – Name of the coordinate to be integrated.

  • start_point (float or None) – Point at which to start the integration. Default is None. If start_point is None, integration starts from the first available point.

  • end_point (float or None) – Point at which to end the integration. Default is None. If end_point is None, integration will continue until the last available point.

  • direction_of_integration (str) – Description of the direction in which to integrate. Options are ‘positive’ or ‘negative’. ‘positive’ corresponds to the values within the array increasing as the array index increases. ‘negative’ corresponds to the values within the array decreasing as the array index increases.

_abc_cache = <_weakrefset.WeakSet object>
_abc_negative_cache = <_weakrefset.WeakSet object>
_abc_negative_cache_version = 213
_abc_registry = <_weakrefset.WeakSet object>
_create_output_cube(template, data, points, bounds)[source]

Populates a template cube with data from the integration

Parameters

  • template (iris.cube.Cube) – Copy of upper or lower bounds cube, based on direction of integration

  • data (list or numpy.ndarray) – Integrated data

  • points (list or numpy.ndarray) – Points values for the integrated coordinate. These will not match the template cube if any slices were skipped in the integration, and therefore are used to slice the template cube to match the data array.

  • bounds (list or numpy.ndarray) – Bounds values for the integrated coordinate

Returns

iris.cube.Cube

_generate_output_name_and_units()[source]

Gets suitable output name and units from input cube metadata

ensure_monotonic_increase_in_chosen_direction(cube)[source]

Ensure that the chosen coordinate is monotonically increasing in the specified direction.

Parameters

cube (iris.cube.Cube) – The cube containing the coordinate to check. Note that the input cube will be modified by this method.

Returns

The cube containing a coordinate that is monotonically increasing in the desired direction.

Return type

iris.cube.Cube

perform_integration(upper_bounds_cube, lower_bounds_cube)[source]

Perform the integration.

Integration is performed by firstly defining the stride as the difference between the upper and lower bound. The contribution from the uppermost half of the stride is calculated by multiplying the upper bound value by 0.5 * stride, and the contribution from the lowermost half of the stride is calculated by multiplying the lower bound value by 0.5 * stride. The contribution from the uppermost half of the stride and the bottom half of the stride is summed.

Integration is performed ONLY over positive values.

Parameters

  • upper_bounds_cube (iris.cube.Cube) – Cube containing the upper bounds to be used during the integration.

  • lower_bounds_cube (iris.cube.Cube) – Cube containing the lower bounds to be used during the integration.

Returns

Cube containing the output from the integration.

Return type

iris.cube.Cube

prepare_for_integration()[source]

Prepare for integration by creating the cubes needed for the integration. These are separate cubes for representing the upper and lower limits of the integration.

Returns

tuple containing:
upper_bounds_cube (iris.cube.Cube):

Cube containing the upper bounds to be used during the integration.

lower_bounds_cube (iris.cube.Cube):

Cube containing the lower bounds to be used during the integration.

Return type

(tuple)

process(cube)[source]

Integrate data along a specified coordinate. Only positive values are integrated; zero and negative values are not included in the sum or as levels on the integrated cube.

Parameters

cube (iris.cube.Cube) – Cube containing the data to be integrated.

Returns

The cube containing the result of the integration. This will have the same name and units as the input cube (TODO same name and units are incorrect - fix this).

Return type

iris.cube.Cube