multiset.py 文件源码

def union_update(self, *others):
        r"""Update the multiset, adding elements from all others using the maximum multiplicity.

        >>> ms = Multiset('aab')
        >>> ms.union_update('bc')
        >>> sorted(ms)
        ['a', 'a', 'b', 'c']

        You can also use the ``|=`` operator for the same effect. However, the operator version
        will only accept a set as other operator, not any iterable, to avoid errors.

        >>> ms = Multiset('aab')
        >>> ms |= Multiset('bccd')
        >>> sorted(ms)
        ['a', 'a', 'b', 'c', 'c', 'd']

        For a variant of the operation which does not modify the multiset, but returns a new
        multiset instead see :meth:`union`.

        Args:
            others: The other sets to union this multiset with. Can also be any :class:`~typing.Iterable`\[~T]
                or :class:`~typing.Mapping`\[~T, :class:`int`] which are then converted to :class:`Multiset`\[~T].
        """
        _elements = self._elements
        _total = self._total
        for other in map(self._as_mapping, others):
            for element, multiplicity in other.items():
                old_multiplicity = _elements.get(element, 0)
                if multiplicity > old_multiplicity:
                    _elements[element] = multiplicity
                    _total += multiplicity - old_multiplicity
        self._total = _total