Re: removing duplicates from a sequence while retainin

for $i in 1 to count($in)
return
  (if ($i = index-of($in, $in[$i])[1]) then $in[$i] else ())

Michael Kay
Saxonica

Dear XSLT list,

Is there an easy way in XPath (not using XSLT instructions) to select only the first occurrence of a specific value in a sequence of atomic values, so as to return the sequence in the original order, but with re-occurrences of each value after the first appearance of that value removed? For example, given an input sequence:

('Matthew','Mark','Luke','Matthew','John')

I want to produce

('Matthew','Mark','Luke','John')

I can't rely on using distinct-values() because that isn't guaranteed to keep specifically the *first* occurrence of a value.

In an XSLT context I can construct a temporary tree, poke each value into an element, all on the same level in the hierarchy, and then test for:

*[not(preceding-sibling::* = .)]

but I don't know how to write an XPath predicate that will filter the sequence of *atomic values* the way I want. Is this just a blind spot? Can anyone advise?

Thanks,

David
djbpitt@xxxxxxxxx