apoc.agg.MaxAndMinItems Maven / Gradle / Ivy

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package apoc.agg;

import apoc.util.Util;
import org.neo4j.procedure.*;

import java.util.ArrayList;
import java.util.List;

/**
 * Aggregation functions for collecting items with only the minimal or maximal values.
 * This is meant to replace queries like this:

 MATCH (p:Person)
 WHERE p.born >= 1930
 WITH p.born as born, collect(p.name) as persons
 WITH min(born) as minBorn, collect({born:born, persons:persons}) as bornInfoList
 UNWIND [info in bornInfoList WHERE info.born = minBorn] as bornInfo
 RETURN bornInfo.born as born, [person in bornInfo.persons | person.name] as persons

 * with an aggregation like this:

 MATCH (p:Person)
 WHERE p.born >= 1930
 WITH apoc.agg.minItems(p, p.born) as minResult
 RETURN minResult.value as born, [person in minResult.items | person.name] as persons

 * returns {born:1930, persons:["Gene Hackman", "Richard Harris", "Clint Eastwood"]}

 */
public class MaxAndMinItems {

    @UserAggregationFunction("apoc.agg.maxItems")
    @Description("apoc.agg.maxItems(item, value, groupLimit: -1) - returns a map {items:[], value:n} where `value` is the maximum value present, and `items` are all items with the same value. The number of items can be optionally limited.")
    public MaxOrMinItemsFunction maxItems() {
        return new MaxOrMinItemsFunction(true);
    }

    @UserAggregationFunction("apoc.agg.minItems")
    @Description("apoc.agg.minItems(item, value, groupLimit: -1) - returns a map {items:[], value:n} where `value` is the minimum value present, and `items` are all items with the same value. The number of items can be optionally limited.")
    public MaxOrMinItemsFunction minItems() {
        return new MaxOrMinItemsFunction(false);
    }


    public static class MaxOrMinItemsFunction {
        private final List