Accept where

Applies a filtering transformation to data variables within the provided data collections. It iterates over the specified collections, groups, and variables, and applies filtering conditions as defined in the ‘where’ expression within the configuration. The resulting filtered variables are added to the data collections.

Args:
    config (dict): A configuration dictionary containing transformation parameters.
    data_collections (DataCollections): An instance of the DataCollections class containing
                                        input data.

Returns:
    None

Raises:
    ValueError: If the 'where' expression format is incorrect.

This is an example of the config dictionary:

Example:
    config = {
        'collections': [...],
        'groups': [...],
        'variables': [...],
        'new name': 'filtered_variable',
        'starting field': 'original_variable',
        'where': ['${collection}::${group}::${variable} >= 0.0']
    }

The configuration components are defined as:

• new name: name of the resulting variable which will be added to data collections

• starting field: original variable which will be filtered using the where condition

• where: an arithmetic filter applied to the specified variable. Note this could be the original_variable or a different variable in data_collections.

Accept where filter for batch processing

To apply the accept where filter to a yaml for batch processing:

transforms:

  - transform: accept where
    new name: collection_name::new_group_name::${variable}
    starting field: collection_name::new_group_name::${variable}
    where:
      - collection_name::filter_group::${variable} == 0
    for:
      variable: *variables

variables are defined in datasets and are referenced in the transform filter. where is a conditional statement (<, >, ==, etc.) with the filter group of choice.

Accept where filter for interactive processing

To apply the accept where filter during an eva interactive session:

    conditions = [filter_group == 0]
    EvaInteractive.accept_where(new_group_name, starting_field, conditions, collection_name)

The parameters for accept_where are

• new_group_name: new name to label transformed group

• starting_field: group in collection that will be transformed

• conditions: a single conditional statement or list of conditional statements

• collection_name: name of the collection that contains group to be transformed