过滤元素,等同于 :func:`bigflow.transforms.filter(self, fn, *side_inputs, **options) `, Args: fn (function): 断言函数 *side_inputs: 参与运算的SideInputs **options: 可配置选项 Returns: PCollection: 过滤结果
(self, fn, *side_inputs, **options)
source not stored for this graph (policy: none)
no outgoing calls