spark graphframes stateful motif

Question

graph frames has a nice example for stateful motifs. How can I explicitly return the counts? As you see the output only contains vertices and friends but not the counts.

How can I modify it to not (only) have access to the edges but access to the labels of the vertices as well?

when(relationship === "friend", cnt + 1).otherwise(cnt)

I.e. how could I enhance the count to count

• the friends of each vertex with age > 30

• the percentage of friendsGreater30 / allFriends

  val g = examples.Graphs.friends  // get example graph
  
  // Find chains of 4 vertices.
  val chain4 = g.find("(a)-[ab]->(b); (b)-[bc]->(c); (c)-[cd]->(d)")
  
  // Query on sequence, with state (cnt)
  //  (a) Define method for updating state given the next element of the motif.
  def sumFriends(cnt: Column, relationship: Column): Column = {
    when(relationship === "friend", cnt + 1).otherwise(cnt)
  }
  //  (b) Use sequence operation to apply method to sequence of elements in motif.
  //      In this case, the elements are the 3 edges.
  val condition = Seq("ab", "bc", "cd").
    foldLeft(lit(0))((cnt, e) => sumFriends(cnt, col(e)("relationship")))
  //  (c) Apply filter to DataFrame.
  val chainWith2Friends2 = chain4.where(condition >= 2)
  

  http://graphframes.github.io/user-guide.html

  chainWith2Friends2.show()
  

Which will output

+-------------+------------+-------------+------------+-------------+------------+--------------+
|            a|          ab|            b|          bc|            c|          cd|             d|
+-------------+------------+-------------+------------+-------------+------------+--------------+
|[e,Esther,32]|[e,d,friend]| [d,David,29]|[d,a,friend]| [a,Alice,34]|[a,e,friend]| [e,Esther,32]|
|[e,Esther,32]|[e,d,friend]| [d,David,29]|[d,a,friend]| [a,Alice,34]|[a,b,friend]|    [b,Bob,36]|
| [d,David,29]|[d,a,friend]| [a,Alice,34]|[a,e,friend]|[e,Esther,32]|[e,d,friend]|  [d,David,29]|
| [d,David,29]|[d,a,friend]| [a,Alice,34]|[a,e,friend]|[e,Esther,32]|[e,f,follow]|  [f,Fanny,36]|
| [d,David,29]|[d,a,friend]| [a,Alice,34]|[a,b,friend]|   [b,Bob,36]|[b,c,follow]|[c,Charlie,30]|
| [a,Alice,34]|[a,e,friend]|[e,Esther,32]|[e,d,friend]| [d,David,29]|[d,a,friend]|  [a,Alice,34]|
+-------------+------------+-------------+------------+-------------+------------+--------------+

Answer 1

Note that sumFriends returns a Column, so condition is a column. This is why you can access it in a where statement without quotes. So all you have to do is add that column to your dataframe. After running the above code, I can run

chain4.withColumn("condition",condition).select("condition").show

+---------+ 
|condition|
+---------+
 | 1|
 | 0|
 | 0|
 | 0|
 | 0|
 | 3|
 | 3|
 | 3|
 | 2|
 | 2|
 | 3|
 | 1|
+---------+

you could also use chain4.select(condition)

Hope this helps