我正在尝试构建一棵介于 0 和 6000 之间的实数树，树的精度变化如下：从 0-100 树深度将继续到小数点后 3 位，即 0 到 99.999，从 100 到 500 将是 2 位小数，500 到 1000 只有 1 位小数，从那里到 6000， 没有小数。 这个想法是，然后我可以用这棵树来表示毫米，升，公斤 - 任何需要实数来定义它的属性。然后我可以将属性单位描述为与实数节点关系中的属性，而不是为 mm、kg 等提供单独的节点集(或者更糟糕的是：长度、宽度、高度 - 所有数千个节点(
我的问题是我无法使条件 FOREACH 循环工作。 生成低至单元级别的节点是一种享受。我在编码方面根本没有经验，我可能错过了一些简单的东西，但我尝试了很多方法，包括首先生成单位精度节点，然后尝试稍后添加更高精度的节点，以及尝试一次性完成所有操作，这似乎更整洁。
MERGE (hub:RealNumber {name:'Real Numbers', mag: 'hub'})
MERGE (zero:RealNumber {name: 0.000, mag: ['eplus3', 'eplus2','eplus1', 'eplus0', 'eminus1', 'eminus2', 'eminus3']})
WITH hub, range(1000,6000,1000) AS thousands, range(100,900,100) AS hundreds,range(10,90,10) AS tens, range(1,9,1) AS units,
range(1,9,1) AS tenths
FOREACH (thousand IN thousands|
FOREACH (hundred IN hundreds |
FOREACH (ten IN tens |
FOREACH (unit IN units |
//FOREACH (tenth in tenths |
MERGE (a1:RealNumber {thousand:thousand, name:toFloat(thousand), mag: 'eplus3'})<-[:TENTHS]-(hub) // creates thousand nodes and connects to hub
MERGE (b1:RealNumber {hundred:hundred, name:toFloat(hundred+a1.name), mag: 'eplus2)'})<-[:TENTHS]-(a1) // creates hunded nodes chid to thousands
MERGE (b2:RealNumber {hundred:hundred, name:toFloat(hundred), mag: 'eplus2'})<-[:TENTHS]-(hub) //creates hundred nodes child to hub
MERGE (c1:RealNumber {ten:ten, name:toFloat(ten+a1.name), mag: 'eplus1'})<-[:TENTHS]-(a1) //creates ten nodes child to thousand >hundreds
MERGE (c2:RealNumber {ten:ten, name:toFloat(ten+b1.name), mag: 'eplus1'})<-[:TENTHS]-(b1)//creates ten nodes child to hundreds
MERGE (c3:RealNumber {ten:ten, name:toFloat(ten+b2.name), mag: 'eplus1'})<-[:TENTHS]-(b2)
MERGE (c4:RealNumber {ten:ten, name:toFloat(ten), mag: 'eplus1'})-[:TENTHS]-(hub) //creates ten nodes child to hub
MERGE (d1:RealNumber {unit:unit, name:toFloat(unit+a1.name), mag: 'eplus0'})<-[:TENTHS]-(a1)
MERGE (d2:RealNumber {unit:unit, name:toFloat(unit+b1.name), mag: 'eplus0'})<-[:TENTHS]-(b1)
MERGE (d3:RealNumber {unit:unit, name:toFloat(unit+b2.name), mag: 'eplus0'})<-[:TENTHS]-(b2)
MERGE (d4:RealNumber {unit:unit, name:toFloat(unit+c1.name), mag: 'eplus0'})<-[:TENTHS]-(c1)
MERGE (d5:RealNumber {unit:unit, name:toFloat(unit+c2.name), mag: 'eplus0'})<-[:TENTHS]-(c2)
MERGE (d6:RealNumber {unit:unit, name:toFloat(unit+c3.name), mag: 'eplus0'})<-[:TENTHS]-(c3)
MERGE (d7:RealNumber {unit:unit, name:toFloat(unit+c4.name), mag: 'eplus0'})<-[:TENTHS]-(c4)
MERGE (d8:RealNumber {unit:unit, name:toFloat(unit), mag: 'eplus0'})<-[:TENTHS]-(hub)
FOREACH (tenth IN tenths IN CASE WHEN a1.thousand<1001 THEN [1] ELSE [] END |
MERGE (e1:RealNumber {tenth:tenth, name:toFloat(tenth)*0.1+a1.name, mag: 'eminus1'})<-[:TENTHS]-(a1) //WHERE e1.name<500
MERGE (e2:RealNumber {tenth:tenth, name:toFloat(tenth)*0.1+b1.name, mag: 'eminus1'})<-[:TENTHS]-(b1)
MERGE (e3:RealNumber {tenth:tenth, name:toFloat(tenth)*0.1+b2.name, mag: 'eminus1'})<-[:TENTHS]-(b2)
MERGE (e4:RealNumber {tenth:tenth, name:toFloat(tenth)*0.1+c1.name, mag: 'eminus1'})<-[:TENTHS]-(c1)
MERGE (e5:RealNumber {tenth:tenth, name:toFloat(tenth)*0.1+c2.name, mag: 'eminus1'})<-[:TENTHS]-(c2)
MERGE (e6:RealNumber {tenth:tenth, name:toFloat(tenth)*0.1+c3.name, mag: 'eminus1'})<-[:TENTHS]-(c3)
MERGE (e7:RealNumber {tenth:tenth, name:toFloat(tenth)*0.1+c4.name, mag: 'eminus1'})<-[:TENTHS]-(c4)
MERGE (e8:RealNumber {tenth:tenth, name:toFloat(tenth)*0.1, mag: 'eminus1'})<-[:TENTHS]-(hub)
)))))
在一个相关的主题上 - 如果我沿着"NEXT_THOUSAND"、"NEXT_HUNDRED"行链接节点，或者只是简单地将它们全部排序并在批次中使用"NEXT"，是否会提高效率？
非常感谢！
可以使用索引快速查找具有一定范围内属性值的节点。不应为一组有限的值创建节点。
使用您评论中提到的引擎示例，假设数据模型如下(每个属性的单位由您固定，不需要存储(：
(:Engine {id: 123, bore: 85.75, stroke: 80, powerDensity: 77.789})
在:Engine(bore)、:Engine(stroke):Engine(powerDensity)上创建索引后，可以有效地执行涉及任何索引属性(或所有索引属性(的查询。
例如：
PROFILE MATCH (e:Engine)
WHERE (80 <= e.bore <= 95.2) AND e.stroke < 85 and e.powerDensity > 75
RETURN e
当在同一MATCH中使用多个索引属性时，只能使用其中一个索引(但密码规划器将尝试选择最有可能获得最快结果的索引(。