pyspark GraphFrames中的主题

Question

我刚接触pyspark，正在努力从GraphFrame中寻找主题。虽然我知道顶点和边之间存在关系，但我得到的结果是空的。我在Cloudera上的Jupyter上用Spark 1.6运行这个。我的顶点和边(以及模式)的屏幕截图位于以下链接中：verticesRDD和edgesRDD

我正在读GraphFrames，但没有读懂...到目前为止，我有以下代码。我哪里错了..？

#import relevant libraries for Graph Frames
from pyspark import SparkContext
from pyspark.sql import SQLContext
from pyspark.sql.functions import desc
from graphframes import *

#Read the csv files 
verticesRDD = sqlContext.read.format("com.databricks.spark.csv").options(header='true', inferschema='true').load("filepath/station.csv")
edgesRDD = sqlContext.read.format("com.databricks.spark.csv").options(header='true', inferschema='true').load("filepath/trip.csv")

#Renaming the id columns to enable GraphFrame 
verticesRDD = verticesRDD.withColumnRenamed("station_ID", "id")
edgesRDD = edgesRDD.withColumnRenamed("Trip ID", "id")
edgesRDD = edgesRDD.withColumnRenamed("Start Station", "src")
edgesRDD = edgesRDD.withColumnRenamed("End Station", "dst")

#Register as temporary tables for running the analysis
verticesRDD.registerTempTable("verticesRDD")
edgesRDD.registerTempTable("edgesRDD")
#Note: whether i register the RDDs as temp tables or not, i get the same epty results... so im not sure if this step is really needed

#Make the GraphFrame
g = GraphFrame(verticesRDD, edgesRDD)

print g
#this deisplays the following:
#GraphFrame(v:[id: int, name: string, lat: double, long: double, dockcount: int, landmark: string, installation: string], e:[src: string, dst: string, id: int, Duration: int, Start Date: string, Start Terminal: int, End Date: string, End Terminal: int, Bike #: int, Subscriber Type: string, Zip Code: string])

#Stations where a is connected to b
motifs = g.find("(a)-[e1]->(b)")
motifs.show()

+---+---+---+
| e1|  a|  b|
+---+---+---+
+---+---+---+

motifs = g.find("(a)-[e1]->(b); (b)-[e2]->(a)")
motifs.show()

+---+---+---+---+
| e1|  a|  b| e2|
+---+---+---+---+
+---+---+---+---+


motifs = g.find("(a)-[e1]->(b); (b)-[e2]->(c)")
motifs.show()

+---+---+---+---+---+
| e1|  a|  b| e2|  c|
+---+---+---+---+---+
+---+---+---+---+---+

#Stations where a is connected to b, b is connected to c 
#but c is not connected to a
motifs = g.find("(a)-[e1]->(b); (b)-[e2]->(c)").filter("(c!=a)")
motifs.show()

+---+---+---+---+---+
| e1|  a|  b| e2|  c|
+---+---+---+---+---+
+---+---+---+---+---+

Answer 1

问题是我如何定义我的顶点。我将"station_id“重命名为"id"，而实际上，它必须是"name”。

verticesRDD = verticesRDD.withColumnRenamed("station_ID", "id")

必须是

verticesRDD = verticesRDD.withColumnRenamed("name", "id")

Motifs可以在这个变化中正常工作！