How to cull elements from a list using Formula

String and list handling are not completely covered in Formula language. Learn how SearchDomino.com member Peter Skold has circumvented that issue by "inventing" a Formula function to cull elements from a list.

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Whether it's because of ignorance or inexperience, I find that string and list handling are not completely covered in Formula language. I often find myself "inventing" functionality that would well defend a permanent place in Formula coding as a built-in function.

I offer to you a widget I sometimes use to cull elements from a list. I've dressed it up for testing. I would appreciate users testing this and responding with suggestions for improvements -- supposing that it is logically sound and fail-safe (I haven't really done that).

If this is already a built-in Formula feature, I haven't seen it thus far. But if it does already exist, I would appreciate any information you have about it.

REM {Keep only elements from one 
list not in the other list -- differentiate them. 
Place this code in an action button or paste the code 
into any text field on a form and enter CTRL+SHIFT+F9 
to execute the code. You may also increase usability by
 converting the lists to lowercase 
using @LowerCase before comparing, for example.};

REM {List1 is the original list in which you wish to keep 
only elements not present in List2, 
it replaces the elements in List2 with "" in List1};

list1 := @Prompt([OkCancelEdit]; 
"Enter list1"; "Please enter a list of elements";
 "summer, winter, spring" );

list1 := @Explode( list1 );

@Prompt([OK] ; "This is your list" ; 
@Implode( @Sort( @Trim( list1 ) ) ; @Newline ) );

list2 := @Prompt([OkCancelEdit]; 
"Which element(s) would you like to remove? 
(from List1)"; "Enter the element(s) here"; 
"summer, winter, leaf");

list2 := @Explode( list2 );

@Prompt([OK] ; "You wish to remove" ; 
@Trim(@Implode(list2 ; @Newline)) );

result := @Replace( list1 ; list2; "");

@Prompt([Ok] ; "Result"  ; 
"Remaining entries: " + @NewLine + 
@Implode(@Sort(result) ; @NewLine ) + 
@NewLine +  @NewLine + "Cleared:" + 
@NewLine + @NewLine + @Implode(@Sort(list2) ; 
@Newline ) + @NewLine + + @NewLine + "** from **" 
+ @NewLine + @NewLine + @Implode(@Sort(list1) ; @Newline) )

MEMBER FEEDBACK TO THIS TIP

You can also use:

@ReplaceSubstring( list1 ; list2 ; "" )) )

For example:

list1 := @Explode( "summer, winter, spring" );
list2 := @Explode( "summer, winter, leaf" ); 
FIELD Exe := Exe; @SetField
("Exe";@Trim(@ReplaceSubstring( list1 ; list2 ; "" )) )

—Bala R.

******************************************

You can also replace @NewLine with @Char(10) throughout the entire formula. Otherwise, all the displays truncate after a single entry.

I don't know if this only occurs on our Lotus Notes installation, but I find that in column formula and @prompts @Char(10) works, whereas @Newline usually doesn't.
—Angelo M.

Do you have comments on this tip? Let us know.

Related information from SearchDomino.com:

  • FAQ: Formula advice
  • Tip: How to create a forgiving Notes/Domino date parser with Formula
  • Tip: Setting row colors by category in a Lotus Notes view
  • Learning Guide: Formula language
  • Reference Center: Formula language for Lotus Notes and Domino

    This tip was submitted to the SearchDomino.com tip library by member Peter Skold. Please let others know how useful it is via the rating scale below. Do you have a useful Lotus Notes, Domino, Workplace or WebSphere tip or code snippet to share? Submit it to our monthly tip contest and you could win a prize.

  • This was first published in December 2006

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