The Union transformation takes a set of inputs and creates a vector of strings as the output.
If one of the inputs is itself a vector, each element in the input vector is associated with one element in the output vector (that is, the transformation does not create a vector of vectors).
Descriptive name of the transformation. You can enter any name here.
Optional. Notes about the transformation.
The conditions under which this transformation is applied.
The default value to use if the condition is met and the input value is not available.
One or more input values.
The name of the output field.
This example uses fields of data from website traffic to create a list of the zip codes associated with the website's visitors (that is, within each log entry). The data provides two possible sources for this information: one in cs-uri-query and the other in a zipcode field of the cookie. If neither of these fields contains a zip code, the default value of 00000 is used.
While it is possible for both of these values to be available in a single log entry, you can select which value to use when you create a dimension based on the transformation's output. In a typical use case, you would create a simple dimension that takes either the first or the last of the encountered values. For information about creating simple dimensions, see Extended Dimensions .