atoti.MultiColumnArrayConversion#

final class atoti.MultiColumnArrayConversion#

Convert an external table where array values are stored with one element per column to a table with array columns.

Groups of a least 2 columns named as "f{prefix}_{index}" (indices being consecutive and starting with 0 or 1) can be converted into array columns.

Example

>>> external_database = session.connect_to_external_database(connection_config)
>>> external_table = external_database.tables["TUTORIAL", "MULTI_COLUMN_QUANTITY"]

external_table has 5 QUANTITY_{index} columns:

>>> list(external_table)
['PRODUCT', 'QUANTITY_0', 'QUANTITY_1', 'QUANTITY_2', 'QUANTITY_3', 'QUANTITY_4']

and its content is:

PRODUCT	QUANTITY_0	QUANTITY_1	QUANTITY_2	QUANTITY_3	QUANTITY_4
product_1	10.0	20.0	15.0	25.0	10.0
product_2	50.0	65.0	55.0	30.0	80.0

It can be converted into a table with an array column:

>>> table = session.add_external_table(
...     external_table,
...     config=TableConfig(
...         array_conversion=tt.MultiColumnArrayConversion(
...             column_prefixes={"QUANTITY"},
...         ),
...         keys={"PRODUCT"},
...     ),
...     table_name="Sales (Multi column array)",
... )
>>> table.head().sort_index()
                                 QUANTITY
PRODUCT
product_1  [10.0, 20.0, 15.0, 25.0, 10.0]
product_2  [50.0, 65.0, 55.0, 30.0, 80.0]