# Identifying duplicate entries in a list

I have a field on a form which is a list of names, and need to check to see if there are any duplicates. I want to do this using a separate calculated field which will list any entries that appear more than once in the source field.

How do I do this using a formula. My best guess is to use the @Unique function and then compare this to the original list, but I'm not if this is possible.

Help would be appreciated!

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Commented:
That is what my formula does.. it returns the duplicates...

list of numbers can be expanded upto any value.. right now it give 100 values.. but it can be increased by appending *+ num to the existing one

eg:
num*+ num*+ num will give 1000 values, num*+ num*+ num*+ num yields 10000 values
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Commented:
Why would you bother to see which are the duplicates ?
Just put in a Translation formula, to get rid of the duplicates :

@unique(TheField)

cheers,

tom
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Groupware ConsultantCommented:
Or, if you really want to know, use
@If(@Elements(TheField)=@Elements(@Unique(TheField)); @Success; @Failure("..."))
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Commented:
Here is the formula to extract duplicates from a List

List := FIELD_NAME_HERE;
num := "0" : "1" : "2" : "3" : "4" : "5" : "6" : "7" : "8" : "9";
idList := @Subset( num*+ num; @Elements(List));
tmp1 := @Unique(@Replace(List; List; idList));
tmp2 := @Trim(@Replace(idList; tmp1; ""));
@Replace(tmp2; idList; List);

~Hemanth
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Author Commented:
My 'list' is actually a concatenation of several list fields - that is why I'm looking for duplicates. I need to return the duplicates themselves - not just a boolean value. This calculated field is going to be displayed on the form as a validation warning -so that users are made aware of the duplicates.

Isn't there a more elegant way of doing it that having to hard code a list of numbers ( There isn't an upper limit to the number of entries in the list, so I don't really want to do this).
I could probably do this using Lotus script, but I just thought it would be simpler using a formula.
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