Union

Developer Documentation Library > UNICOM Intelligence Function Library > Categorical functions > Union

Union

Returns the union of two or more category lists--that is, it returns all of the categories that are in any one or more of the category lists.

Syntax

Union(<value> [, <values>, ...])

Parameters

<value>

Type: Categorical

Categorical value.

Type: None

One or more variant values of type Categorical or Text. Each value specifies a set of categories.

(return)

Type: Categorical

All of the categories in <value>, followed by any other categories that are in <values>.

Notes

If an item is NULL, the item is ignored. If the current value is NULL, <value> is an empty Categorical value ({}) and the return value is the union of all non-NULL items in <values>.

This function is equivalent to the Addition (+) operator+ for Categorical values, except that Union can operate on named categories and the NULL behavior is different. However, using the + operator is generally faster than using the Union function.

Examples

Function call	Q1	Q2	Result
Union(Q1, Q2)	{5,1,6,3,2,4}	{3,6,7,5}	{5,1,6,3,2,4,7}
Q1.Union(Q2)	{4,2,9,6,1,7}	{}	{4,2,9,6,1,7}

Function call	Q1	Q2	Q3	Result
Q1.Union(Q2, Q3)	{6,8,2,3}	{3,4,6}	{1,7,8}	{6,8,2,3,4,1,7}
Union(Q1, Q2, Q3)	{6,8,2,3}	{3,4,6}	NULL	{6,8,2,3,4}

The following example uses Union to combine the results of two single response categorical variables that have similar category lists and tests whether the result includes the Yes category. For example, you could use this example to select respondents who chose Yes in response to at least one of the questions.

Union(biology, education) >= {yes}