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GroupBy

KNIME Base Nodes version 4.0.2.v201909251340 by KNIME AG, Zurich, Switzerland

Groups the rows of a table by the unique values in the selected group columns. A row is created for each unique set of values of the selected group column. The remaining columns are aggregated based on the specified aggregation settings. The output table contains one row for each unique value combination of the selected group columns.

The columns to aggregate can be either defined by selecting the columns directly, by name based on a search pattern or based on the data type. Input columns are handled in this order and only considered once e.g. columns that are added directly on the "Manual Aggregation" tab are ignored even if their name matches a search pattern on the "Pattern Based Aggregation" tab or their type matches a defined type on the "Type Based Aggregation" tab. The same holds for columns that are added based on a search pattern. They are ignored even if they match a criterion that has been defined in the "Type Based Aggregation" tab.

The "Manual Aggregation" tab allows you to change the aggregation method of more than one column. In order to do so select the columns to change, open the context menu with a right mouse click and select the aggregation method to use.

In the "Pattern Based Aggregation" tab you can assign aggregation methods to columns based on a search pattern. The pattern can be either a string with wildcards or a regular expression. Columns where the name matches the pattern but where the data type is not compatible with the selected aggregation method are ignored. Only columns that have not been selected as group column or that have not been selected as aggregation column on the "Manual Aggregation" tab are considered.

The "Type Based Aggregation" tab allows to select an aggregation method for all columns of a certain data type e.g. to compute the mean for all decimal columns (DoubleCell). Only columns that have not been handled by the other tabs e.g. group, column based and pattern based are considered. The data type list to choose from contains basic types e.g String, Double, etc. and all data types the current input table contains.

A detailed description of the available aggregation methods can be found on the 'Description' tab in the node dialog.

Options

Groups

Group settings
Select one or more column(s) according to which the group(s) is/are created.

Advanced settings

Maximum unique values per group
Defines the maximum number of unique values per group to avoid problems with memory overloading. All groups with more unique values are skipped during the calculation and a missing value is set in the corresponding column, and a warning is displayed.
Column naming
The name of the resulting aggregation column(s) depends on the selected naming schema.
  • Keep original name(s): Keeps the original column names. Note that you can use all aggregation columns only once with this column naming option to prevent duplicate column names.
  • Aggregation method (column name): Uses the aggregation method first and appends the column name in brackets
  • Column name (aggregation method): Uses the column name first and appends the aggregation method in brackets
All aggregation methods get a * appended if the missing value option is not ticked in the aggregation settings in order to distinguish between columns that considered missing values in the aggregation process and columns that do not.
Enable hiliting
If enabled, the hiliting of a group row will hilite all rows of this group in other views. Depending on the number of rows, enabling this feature might consume a lot of memory.
Value delimiter
The value delimiter used by aggregation methods such as concatenate.
Process in memory
Process the table in the memory. Requires more memory but is faster since the table needs not to be sorted prior aggregation. The memory consumption depends on the number of unique groups and the chosen aggregation method. The row order of the input table is automatically retained.
Retain row order
Retains the original row order of the input table. Could result in longer execution time. The row order is automatically retained if the process in memory option is selected.

Manual Aggregation

Aggregation settings
Select one or more column(s) for aggregation from the available columns list. Change the aggregation method in the Aggregation column of the table. You can add the same column multiple times. In order to change the aggregation method of more than one column select all columns to change, open the context menu with a right mouse click and select the aggregation method to use.
Missing
Missing values are considered during aggregation if the missing option is ticked for the corresponding row in the column aggregation table. Some aggregation methods do not support the changing of the missing option such as means.
Parameter
The parameter column shows an "Edit" button for all aggregation operators that require additional information. Clicking on the "Edit" button opens the parameter dialog which allows changing the operator specific settings.

Pattern Based Aggregation

Aggregation settings
Use the "Add" button to add a new row with a search pattern to the aggregation settings. The search pattern can either be a string with wildcards or a regular expression. Supported wildcards are * (matches any number of characters) and ? (matches one character) e.g. KNI* would match all strings that start with KNI such as KNIME whereas KNI? would match only strings that start with KNI followed by a fourth character. Double click the "Search pattern" cell to edit the pattern. The cell is colored in red if the pattern is invalid.
RegEx
Tick this option if the search pattern is a regular expression otherwise it is treated as string with wildcards ('*' and '?').
Missing
Missing values are considered during aggregation if the missing option is ticked for the corresponding row in the column aggregation table. Some aggregation methods do not support the changing of the missing option such as means.
Parameter
The parameter column shows an "Edit" button for all aggregation operators that require additional information. Clicking on the "Edit" button opens the parameter dialog which allows changing the operator specific settings.

Type Based Aggregation

Aggregation Settings
Select one or more data type from the available type list. Change the aggregation method in the Aggregation column of the table. You can add the same data type multiple times. The list contains standard types e.g. Double, String etc. and all types of the input table.
Missing
Missing values are considered during aggregation if the missing option is ticked for the corresponding row in the column aggregation table. Some aggregation methods do not support the changing of the missing option such as means.
Parameter
The parameter column shows an "Edit" button for all aggregation operators that require additional information. Clicking on the "Edit" button opens the parameter dialog which allows changing the operator specific settings.
Type matching
  • Strict: the type based aggregation method is only applied to columns of the selected type.
  • Include sub-types: the type based aggregation method is also applied to columns containing sub-types of the selected type. For example Boolean is a sub-type of Integer, Integer of Long, and Long of Double.

Input Ports

The input table to group.

Output Ports

Result table with one row for each existing value combination of the selected columns.

Best Friends (Incoming)

Best Friends (Outgoing)