Function reducer

tests/python/common/function/test_basics.py:776–779

(nodes)

    g.edata["eid"] = F.copy_to(F.arange(0, 10), F.ctx())

    def reducer(nodes):
        eid = F.asnumpy(F.copy_to(nodes.mailbox["eid"], F.cpu()))
        assert np.array_equal(eid, np.sort(eid, 1))
        return {"n": F.sum(nodes.mailbox["eid"], 1)}

    g.update_all(fn.copy_e("eid", "eid"), reducer)