UnionList ( ListA ; ListB )

Logical union of two lists of values

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Rob Poelking - Show more from this author
Kiza Solutions
https://kizasolutions.com

Sample input:

UnionList ( List ( "apple" ; "pear" ; "orange" ) ; List ( "pear" ; "banana" ; "mango" ) )

Sample output:

apple
pear
orange
banana
mango

Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

/**
 * ==================================================================
 * UnionList ( ListA ; ListB  )
 *
 * PARAMETERS:
 *            @ListA (text) list of paragraph separated values
 *            @ListB (text) list of paragraph separated values
 *            @leaveBlank (text) leave blank; allows tail recursion - no longer needed
 * RETURNS:
 *            (text) list of distinct values from lists A & B
 *            
 * DEPENDENCIES:
 *            Version FM 18 or higher
 * PURPOSE:
 *            performs a logical union of two lists omitting
 *            duplicates
 * NOTES:
 *            none
 * AUTHOR:
 *            Rob Poelking
 * REVISIONS:
 * REVISIONS:
              2020-06-17 V2 revised and optimized for While - original version left for older version of FM
 *            2014-07-02 Rob Poelking - initial release
 * ==================================================================
 *
 */


While ( 
	[ 
		//ListA = List ( "apple" ; "pear" ; "orange" ) ;
		//ListB = List ( "pear" ; "banana" ; "orange" ; "grapefruit" ) ;
		~wholeList = List ( ListA ; ListB ) ;
		~count = Valuecount ( ~wholeList ) ; 
		~newList = "" ;
		~i = 0 
	] ; 
	~i < ~count ; 
	[ 
		~i=~i+1 ;
		~thisValue = getvalue ( ~wholeList ; ~i );
		~addValue = if ( position (~newList ; ~thisValue ; 1 ; 1) ; "" ; ~thisValue) ;
		~newList = list ( ~newList ; ~addValue )
	] ; 
	~newList 
)

/*

Let ( [
	wholeList = List ( ListA ; ListB ) ;
	valCount = ValueCount ( wholeList ) ;
	value = GetValue ( wholeList ; 1 ) ;
	tempList = If ( Position ( leaveBlank ; value ; 1 ; 1 ) ; leaveBlank ; List ( leaveBlank ; value ) ) ;
	newList = tempList 
	] ;
		
		If ( valCount > 0 ; 
			UnionList ( RightValues ( wholeList ; valcount - 1 ) ; "" ; newList ) ; 
			newList )

)

// original version left for FileMaker 17 or less. Include the "leaveBlank" parameter for tail recursion
/*

Simple function that uses tail recursion to perform a logical union of two list omitting duplicates.

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UnionList ( ListA ; ListB )

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