Collection Cookbook

The goal of the workflow is to demonstrate the creation and working with collection cells. It is divided into three parts:

1. "Collection creation and conversion" part shows how collection columns can be generated by combining rows e.g. by grouping them in the GroupBy node or columns e.g. by combining them in the Column Aggregator node.

2. "Collection types" section describes the two different collection types that are supported by KNIME namely
- Lists: list all elements including duplicates in the order they were added to the collection.
- Sets: list the elements in an arbitrary order but contain each element only once.

3. "Working with collections" demonstrates a sub set of the nodes that support collections such as the Item Set Finder (Borgelt) node which searches in a collection column for frequently co-occuring elements.

General infos

The KNIME data table outport view displays by default only the first part of a collection cell. If you want to view all elements of a collection change the cell renderer via the column context menu.

To open the context menu click right-click the column header e.g. (...)Characters in the table outport view of the top left GroupBy node.
Select the Collection(full) renderer from the available renderes.
Note that other data types allow you to change the cell renderer as well e.g. multi line renderer for string or full precision renderer for double values.