Neo4j cypher getting nodes that are related to another node using ALL relations

Question

I am doing a PoC to find out if a graph database will fit our needs.

We have a survey in which respondents have answered questions. We want to group these respondents using every possible combination of answers out of a set of (mostly two or three) questions.

I have the following nodes and relationships

(:Question)-[:HasAnswer]->(:Answer)
(:Respondent)-[:Answered]->(:Answer)
(:Answer)-[:BelongsTo]->(:WeightingGroup)

In which:

Question: the question
Answer: A possible answer to a question
Respondent: A person that answered questions
Answered: The relation between a respondent that answered a question
WeightingGroup: A group of answers that form unique combinations of given answers
BelongsTo: The relationship between an answer and a weightinggroup to form groups of answers.

My goal is to receive a result like this:

/----------------------------------------------\
| Q1                 | Q2                 | n  |
|--------------------+-------------------------|
| Answer1            | Answer1            | 23 | 
| Answer1            | Answer2            | 12 | 
| Answer1            | Answer3            | 54 | 
| Answer2            | Answer1            | 65 | 
| Answer2            | Answer1            |  5 | 
| Answer2            | Answer1            | 15 | 
\--------------------+--------------------+----/

or:

/-------------------------\
| Q1, Q2             | n  |
|--------------------+----|
| Answer1, Answer2   | 23 | 
| Answer1, Answer2   | 12 | 
| Answer1, Answer3   | 54 | 
| Answer2, Answer1   | 65 | 
| Answer2, Answer1   |  5 | 
| Answer2, Answer1   | 15 | 
\--------------------+----/

Where n is the number of respondents that gave both answers.

However, when I run this query:

// Aantal antwoorden per wegingsgroep
match (w:WeightingGroup)-[]->(a:Answer)<-[:Answered]-(r:Respondent)
with w, collect(distinct a.Text) as answers, count(distinct r) as n
return answers, w.Weight, n

It seems to be returning n = the number of respondents that answered answer1 OR answer2.

How do get the count of Respondents that gave answer1 AND answer2?

Thanks in advance!

If I understood your requirement correctly just add "WHERE length(answers) > 1" clause to your query. — František Hartman
– František Hartman, Commented Feb 28, 2014 at 16:28
please put a small sample dataset on console.neo4j.org and share it — Stefan Armbruster
– Stefan Armbruster, Commented Mar 1, 2014 at 9:07

jjaderberg · Accepted Answer · 2014-03-01 17:45:47Z

3

How about something like this: collect answers per group, collect answers per respondent, filter on where all answers for a respondent are present in the answers for a group. I think then the count on respondent should be ok (you'll have to extract the answer texts since the answers are already collected.)

MATCH (g:WeightingGroup)<-[:BelongsTo]-(a)
WITH g, collect(a) as apg
MATCH (r:Respondent)-[:Answered]->(a)
WITH g, apg, r, collect(a) as apr
WHERE ALL(a IN apr WHERE a IN apg)
RETURN g.Weight, EXTRACT(a IN apg | a.Text), count(r) as n

answered Mar 1, 2014 at 17:45

jjaderberg

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3 Comments

Koen Schepens Over a year ago

Thanks for the answer! And sorry for the late response (carnaval came in between ;)) I tried this query but it crashed neo4J (taking all CPU and 2GB memory). This probably has to do with the fact that the database contains over 600.000 given answers.

jjaderberg Over a year ago

Is that 600k possible answers across your questions, and every combination of them is an answer group? I think the query works but you may need to restructure the data or do the analysis in steps.

Koen Schepens Over a year ago

Sorry, I meant 6,000,000 given answers. I tried your query on a sample dataset and it did give me the desired results so will mark it as accepted answer :) My Neo4j community however now refuses to start at all so I guess I seriously broke something :(

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