saxon:highest
Finds the items having the highest value for some expression.
highest($input as item()*) ➔ item()*
Arguments | |||
| $input | item()* | The input sequence |
Result | item()* | ||
highest($input as item()*, $key as function(item()) as xs:anyAtomicType?) ➔ item()*
Arguments | |||
| $input | item()* | The input sequence |
| $key | function(item()) as xs:anyAtomicType? | Function to compute the sort key |
Result | item()* | ||
Namespace
http://saxon.sf.net/
Saxon availability
Requires Saxon-PE or Saxon-EE.
Notes on the Saxon implementation
Available since before Saxon 8.0. Changed in Saxon 9.5 to take a function rather than an expression as the second argument. Changed in 9.9 to allow the sort key to be an empty sequence, and to define the result of edge cases more precisely.
Details
This function returns the item or items from the input sequence that have the highest
value for the function $key. If the second argument is omitted, it defaults
to the function fn:data#1, that is, it atomizes the item from the input
sequence.
The $key function is evaluated for each item in $input in
turn, with that item supplied as the parameter to the function. Any items for which the
sort key evaluates to an empty sequence or to NaN are
ignored. If the input sequence is empty, the result is an empty sequence. If several
items have the highest value, the result sequence contains them all, retaining the original order.
Any computed key that is of type xs:untypedAtomic is converted to xs:double.
Strings are compared using the default collation from the static context.
An error occurs if any key belongs to an unordered type (such as xs:QName) or if two
keys belong to types that are not comparable (for example xs:integer and xs:string).
Example: saxon:highest(sale, function($x){$x/@price * $x/@qty}) will
evaluate price times quantity for each child <sale> element, and
return the element or elements for which this has the highest value.