MaxDepth param for Breadth-first search

[tomasonjo]

It looks like the DFS algorithm has the maxDepth parameter that includes the max value while the BFS algorithm does not include it. This can be confusing to an end user.

Create graph:

MERGE (nAlice:User {id:'Alice'})
MERGE (nBridget:User {id:'Bridget'})
MERGE (nCharles:User {id:'Charles'})
MERGE (nDoug:User {id:'Doug'})
MERGE (nMark:User {id:'Mark'})
MERGE (nMichael:User {id:'Michael'})

MERGE (nAlice)-[:FOLLOW]->(nBridget)
MERGE (nAlice)-[:FOLLOW]->(nCharles)
MERGE (nBridget)-[:FOLLOW]->(nMichael)
MERGE (nDoug)-[:FOLLOW]->(nMark)
MERGE (nAlice)-[:FOLLOW]->(nMichael)
MERGE (nCharles)-[:FOLLOW]->(nDoug);

BFS

MATCH (s:User{id:'Bridget'}) 
WITH id(s) as start_id 
CALL algo.bfs.stream('User', 'FOLLOW', 'BOTH', start_id, 
{maxDepth:2}) YIELD nodeIds 
UNWIND nodeIds as nodeId 
RETURN algo.asNode(nodeId).id as user

results:

user
"Bridget"
"Alice"
"Michael"

DFS

MATCH (s:User{id:'Bridget'}) 
WITH id(s) as start_id 
CALL algo.dfs.stream('User', 'FOLLOW', 'BOTH', start_id, 
{maxDepth:2}) 
YIELD nodeIds 
UNWIND nodeIds as nodeId 
RETURN algo.asNode(nodeId).id as user

results:

user
"Bridget"
"Michael"
"Alice"
"Charles"

[tomasonjo]

I inspected the code a bit and it is a simple difference in the comparing operator:

DFS:

exitFunction = (s, t, w) -> w > maxDepth ? Traverse.ExitPredicate.Result.CONTINUE : Traverse.ExitPredicate.Result.FOLLOW;
BFS:

exitFunction = (s, t, w) -> w >= maxDepth ? Traverse.ExitPredicate.Result.CONTINUE : Traverse.ExitPredicate.Result.FOLLOW;