How do you identify duplicate values in a numerical sequence using XPath 2.0?
I have an XPath expression which provides me a sequence of values like the one below:
1 2 2 3 4 5 5 6 7
It is easy to convert this to a set of unique values 1 2 3 4 5 6 7 using distinct-values() . However, what I want to extract is the list of duplicate values = 2 5. I can't think of an easy way to do this. Can anyone help?
Answer
Use this simple XPath 2.0 expression:
$vSeq[index-of($vSeq,.)[2]]
where $vSeq is the sequence of values in which we want to find the duplicates.
For explanation of how this "works", see:
TLDR; This picture can be a visual explanation.
If the sequence is:
$vSeq = 1, 2, 3, 2, 4, 5, 6, 7, 5, 7, 5
Then evaluating the above XPath expression produces: 2, 5, 7
