protected static Object fieldValue(DapSequence seq, DataRecord record, String field)
throws DapException {
DapVariable dapv = seq.findByName(field);
if (dapv == null) throw new DapException("Unknown variable in filter: " + field);
if (dapv.getSort() != DapSort.ATOMICVARIABLE)
throw new DapException("Non-atomic variable in filter: " + field);
if (dapv.getRank() > 0) throw new DapException("Non-scalar variable in filter: " + field);
DataAtomic da = (DataAtomic) (record.readfield(field));
if (da == null) throw new DapException("No such field: " + field);
return da.read(0);
}
