# Re: Finding the position of node in foreign node list

 Subject: Re: Finding the position of node in foreign node list From: Dimitre Novatchev Date: Fri, 4 Mar 2005 13:15:10 +1100
```David C. and Joris already showed possible solutions.

The time complexity of these ssolutions would most probably be close to:

O(count(\$A) * count(\$B))

If \$A and \$B are sufficiently large, more efficient algorithms exist,
e.g. with time complexity close to:

O(log(\$A) * count(\$B) )

See for example the implementation of set:leading() (in EXSLT for MSXML4) at:

http://www.xml.com/pub/a/2003/08/06/exslt.html?page=2

Cheers,

Dimitre Novatchev.

> Hi
>
> Here is a problem I'm playing around with:
>
> I have two variables containing two sets of nodes.
>
> \$A contains 5 elements A,B,C,D,E of element type Service
>
> \$B contains a subset of A\$ e.g 2 elements B and D
>
> I am using them to create a table which looks like this
>
>    A    B    C    D    E  (Table header, which comes from \$A)
>          B          D        (First table row, which comes from \$B)
>
> \$B is reset though a for-each loop, which then loops to fill the table:
>
> A    B    C    D    E
>      B          D
> A          C    D
>                        E
> and so on.
>
> The for each which runs through the table, builds the table by running
> though each element in \$A and checking to see if it exists in \$B. If so, the
> value written.
>
> I need to determine the positional value of the element being written, as it
> occurs in the in the variable \$B
>
> If I just use the postion function, I get the position value from the
> superset variable \$A
>
> so I get output like this:
>
> A    B    C    D    E
>       2          4
> 1           3    4
>                         5
>
> The ouput I am looking for should rather list the position as it occurs in
> the subset variable \$B:
>
> A    B    C    D    E
>       1          2
> 1           2    3
>                         1
>
> Any ideas how I can find out what the position of the current node is in a
> foreign node set? (As opposed to the position in the current node set)
>
> Thanks.
>

```

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