MARCXML field and subfield frequencies

marcxml_field_frequency.xquery

xquery version "3.0";

declare default element namespace "http://www.loc.gov/MARC21/slim";
declare option saxon:output "omit-xml-declaration=yes";
declare option saxon:output "method=text";

declare variable $records := /collection/record;
declare variable $total := count($records);

string-join(
    for $record in $records,
        $field in $record/(controlfield|datafield),
        $subfield allowing empty in $field/subfield/@code
    group by $field_tag := $field/@tag, $subfield
    let $count := count(distinct-values($record))
    order by $count descending
    return (
      text{string-join((string($field_tag), $subfield, string(round($count div $total, 4))), ",")}
    ),
    text{"
"}
)