Skip to main content

​
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:
PRODUCTQUANTITY_0QUANTITY_1QUANTITY_2QUANTITY_3QUANTITY_4
product_11020152510
product_25065553080
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]
See also: AutoMultiColumnArrayConversion

​
column_prefixes : Set[str]

The prefixes of the array element columns in the external table. One array column per prefix will be created.