Re: [xsl] XPath expression that returns a sequence of pairs?

["Martin Honnen martin.honnen@xxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

On 1/17/2023 9:08 PM, Roger L Costello costello@xxxxxxxxx wrote:
> Hi Folks,
>
> I have this XML document:
>
> <Track-History>
>      <Track-ID>XYZ</Track-ID>
>      <Observation>
>          <Target-Latitude>10</Target-Latitude>
>          <Target-Longitude>20</Target-Longitude>
>          <Observer-Latitude>40</Observer-Latitude>
>          <Observer-Longitude>50</Observer-Longitude>
>      </Observation>
>      <Observation>
>          <Target-Latitude>15</Target-Latitude>
>          <Target-Longitude>25</Target-Longitude>
>          <Observer-Latitude>40</Observer-Latitude>
>          <Observer-Longitude>50</Observer-Longitude>
>      </Observation>
> </Track-History>
>
> I want an XPath expression that returns a sequence of (Target-Latitude,
Target-Longitude) pairs; i.e., a pair for each <Observation> element. For the
XML document shown above, the XPath should return this sequence:
> (10,20), (15,25)
>
> A count of the number of items in the sequence should yield: 2
>
> The following XPath is not correct:
>
> for $i in //Observation return ($i/Target-Latitude, $i/Target-Longitude)
>
> A count of the number of items returned by that XPath yields: 4
>
> Is there an XPath to do what I seek?

In XPath 3.1 use a sequence of maps e.g.

B  //Observation/map { 'lat' : data(Target-Latitude), 'long' :
data(Target-Longitude) }


then you can process e.g.

B  let $maps := //Observation/map { 'lat' : data(Target-Latitude),
'long' : data(Target-Longitude) }

B  return for $map in $maps

B  return ($map?lat, $map?long)