using Dijkstra with calculated properties

[neo-technology-build-agent]

Issue by rvanbruggen
Tuesday Aug 23, 2016 at 10:15 GMT
Originally opened as neo4j-contrib/neo4j-apoc-procedures#119

---

I would like to run the apoc.algo.dijkstra with a cost function that is calculated based on 2 properties of the relationships. I have
(a)-[r:RELTYPE {prop1:x, prop2:y})->(b)
and would like to do
call apoc.algo.dijkstra(a,b,'RELTYPE',prop1/prop2) yield path, weight
or something like that. I can of course persist the calculated property and do dijkstra over that new property, but it would be nice if you did not have to do that.

[neo-technology-build-agent]

Comment by jexp
Wednesday Aug 24, 2016 at 20:29 GMT

---

We can provide an arbitrary Cypher expression that is then executed with the following things passed in: start-, end-node of relationship, relationship, path

call apoc.algo.dijkstra(a,b,'RELTYPE','rel.prop1/r.prop2`) yield path, weight

is turned into something like this:
WITH {relationship} as r, {startNode} as s,{endNode} as e, {path} as p RETURN rel.prop1/r.prop2 as weight

I wonder if shorter variable names are better like r or more descriptive ones like rel, relationship, lastRelationship.

Oh and where available we can use the compiled Cypher runtime to make this really fast :)

For simple operations though this all might be overkill and we "could" implement a basic expression handler for addition, multiplication, division, subtraction ?

[neo-technology-build-agent]

Comment by fbiville
Thursday Apr 29, 2021 at 16:01 GMT

---

@rvanbruggen it seems GDS has the same limitation. Should we transfer the issue to GDS? What do you think?

[vga91]

[Essential builds failure] apoc.warmup.WarmupEnterpriseTest.testWarmupOnEnterpriseStorageEngine is failing on a Dev essential build