Neo4j: Allow REDUCE to work with maps

[rickardoberg]

I would like Cypher REDUCE to work with a map as an accumulator. As input I have a list of tuples (key,value) which I want to convert into a map.

Something like this:
REDUCE(map={}, row IN coll | SET map[row.key]=row.value)

[jexp]

I'd prefer

REDUCE(map={}, row IN coll | map + { (row.key) : row.value})

Am 22.08.2016 um 10:36 schrieb Rickard Öberg [email protected]:

I would like Cypher REDUCE to work with a map as an accumulator. As input I have a list of tuples (key,value) which I want to convert into a map.

Something like this:
REDUCE(map={}, row IN coll | SET map[row.key]=row.value)

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[swayam18]

any updates on this issue?

[freeeve]

apoc helps these days:

with [{a:1, x:'y'}, {b:2, y:'z'}] as coll
return reduce(acc={}, x in coll | apoc.map.merge(acc, x))

[sherfert]

Reduce works with any accumulator, what is missing from Cypher is a way to to merge maps. For this I refer to this feature request: https://github.com/neo4j/neo4j/issues/4470

But, since APOC already provides such functions:

apoc.map.merge(base, patch)
apoc.map.updateTree(tree, key, value)

we currently don't consider adding these functions into Neo4j.