单源最短路径使用Dijkstra算法,给定起点,输出该点和其他所有节点的最短路径。本文为您介绍PAI-Studio提供的单源最短路径组件。

PAI-Studio支持通过可视化或PAI命令方式,配置单源最短路径组件的参数。

可视化方式

页签 参数 描述
字段设置 选择源顶点列 边表的起点所在列。
选择目标顶点列 边表的终点所在列。
选择边权值列 边表边的权重所在列。
参数设置 起始节点 ID 用于计算最短路径的起始节点,必填。
执行调优 进程数 作业并行执行的节点数。数字越大并行度越高,但框架通讯开销框架通讯开销是什么意思会增大。
进程内存 单个作业可使用的最大内存量。系统默认为每个作业分配4096 MB内存,实际使用内存超过该值,会抛出OutOfMemory异常。

PAI命令方式

PAI -name SSSP
    -project algo_public
    -DinputEdgeTableName=SSSP_func_test_edge
    -DfromVertexCol=flow_out_id
    -DtoVertexCol=flow_in_id
    -DoutputTableName=SSSP_func_test_result
    -DhasEdgeWeight=true
    -DedgeWeightCol=edge_weight
    -DstartVertex=a;
参数 是否必选 描述 默认值
inputEdgeTableName 输入边表名。
inputEdgeTablePartitions 输入边表的分区。 全表读入
fromVertexCol 输入边表的起点所在列。
toVertexCol 输入边表的终点所在列。
outputTableName 输出表名。
outputTablePartitions 输出表的分区。
lifecycle 输出表的生命周期。
workerNum 作业并行执行的节点数。数字越大并行度越高,但框架通讯开销框架通讯开销是什么意思会增大。 未设置
workerMem 单个作业可使用的最大内存量。系统默认为每个作业分配4096 MB内存,实际使用内存超过该值,会抛出OutOfMemory异常。 4096
splitSize 数据切分大小。 64
startVertex 起始节点ID。
hasEdgeWeight 输入边表的边是否有权重。 false
edgeWeightCol 输入边表边的权重所在列。

使用示例

  1. 生成训练数据。
    drop table if exists SSSP_func_test_edge;
    create table SSSP_func_test_edge as
    select
        flow_out_id,flow_in_id,edge_weight
    from
    (
        select "a" as flow_out_id,"b" as flow_in_id,1.0 as edge_weight from dual
        union all
        select "b" as flow_out_id,"c" as flow_in_id,2.0 as edge_weight from dual
        union all
        select "c" as flow_out_id,"d" as flow_in_id,1.0 as edge_weight from dual
        union all
        select "b" as flow_out_id,"e" as flow_in_id,2.0 as edge_weight from dual
        union all
        select "e" as flow_out_id,"d" as flow_in_id,1.0 as edge_weight from dual
        union all
        select "c" as flow_out_id,"e" as flow_in_id,1.0 as edge_weight from dual
        union all
        select "f" as flow_out_id,"g" as flow_in_id,3.0 as edge_weight from dual
        union all
        select "a" as flow_out_id,"d" as flow_in_id,4.0 as edge_weight from dual
    ) tmp;
    对应的图结构如下所示。单源最短路径图结构
  2. 查看训练结果。
    +------------+------------+------------+--------------+
    | start_node | dest_node  | distance   | distance_cnt |
    +------------+------------+------------+--------------+
    | a          | b          | 1.0        | 1            |
    | a          | c          | 3.0        | 1            |
    | a          | d          | 4.0        | 3            |
    | a          | a          | 0.0        | 0            |
    | a          | e          | 3.0        | 1            |
    +------------+------------+------------+--------------+