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Generate Attributes

Synopsis​

This operator constructs new user defined attributes using mathematical expressions.

Description​

The Generate Attributes operator constructs new attributes from the attributes of the input ExampleSet and arbitrary constants using mathematical expressions. The attribute names of the input ExampleSet might be used as variables in the mathematical expressions for new attributes. During the application of this operator these expressions are evaluated on each example, these variables are then filled with the example's attribute values. Thus this operator not only creates new columns for new attributes, but also fills those columns with corresponding values of those attributes. If a variable is undefined in an expression, the entire expression becomes undefined and '?' is stored at its location.

Please note that there are some restrictions for the attribute names in order to let this operator work properly:

  • Attribute names containing dashes '-' or other special characters, or having the same name as a constant (e.g. 'e' or 'pi') must be placed in square brackets e.g. '[weird-name]' or '[pi]'.
  • Attribute names containing square brackets or backslashes must be placed in square brackets and the square brackets and backslashes inside the name must be escaped, e.g. '[a\tt[1]]' for an attribute 'a\tt[1]'.

If you want to apply this operator but the attributes of your ExampleSet do not fulfill above mentioned conditions you can rename attributes with the <reference key="operator.blending:rename">Rename</reference> operator before application of the Generate Attributes operator. When replacing several attributes following a certain schema, the Rename by Replacing operator might prove useful.

A large number of operations and functions is supported, which allows you to write rich expressions. For a list of operations and functions and their descriptions open the Edit Expression dialog. Complicated expressions can be created by using multiple operations and functions. Parenthesis can be used to nest operations.

This operator also supports various constants (for example 'INFINITY', 'PI' and 'e'). Again you can find a complete list in the Edit Expression dialog. You can also use strings in operations but the string values should be enclosed in double quotes (").

Input​

example set​

This input port expects an ExampleSet. It is the output of the Rename operator in the attached Example Process. The output of other operators can also be used as input.

Output​

example set​

The ExampleSet with new attributes is output of this port.

original​

The ExampleSet that was given as input is passed without changing to the output through this port. This is usually used to reuse the same ExampleSet in further operators or to view the ExampleSet in the results workspace.

Parameters​

Function descriptions​

The list of functions for generating new attributes is provided here.

Keep all​

If set to true, all the original attributes are kept, otherwise they are removed from the output ExampleSet.