列表函数

Nebula Graph支持以下列表（List）函数。

函数说明
keys(expr)返回一个列表，包含字符串形式的点、边或映射的所有属性。
labels(vertex)返回点的标签列表。
nodes(path)返回路径中所有点的列表。
range(start, end [, step])返回[start,end]范围内固定步长的列表，默认步长step为1。
relationships(path)返回路径中所有关系的列表。
reverse(list)返回将原列表逆序排列的新列表。
tail(list)返回不包含原列表第一个元素的新列表.
head(list)返回列表的第一个元素。
last(list)返回列表的最后一个元素。
coalesce(list)返回列表中第一个非空元素。
reduce()请参见reduce函数。

说明：如果参数为NULL，则输出结果是未定义的。

示例

  1. nebula> WITH [NULL, 4923, 'abc', 521, 487] AS ids \
  2.         RETURN reverse(ids), tail(ids), head(ids), last(ids), coalesce(ids);
  3. +-----------------------------------+-------------------------+-----------+-----------+---------------+
  4. | reverse(ids)                      | tail(ids)               | head(ids) | last(ids) | coalesce(ids) |
  5. +-----------------------------------+-------------------------+-----------+-----------+---------------+
  6. | [487, 521, "abc", 4923, __NULL__] | [4923, "abc", 521, 487] | __NULL__  | 487       | 4923          |
  7. +-----------------------------------+-------------------------+-----------+-----------+---------------+
  9. nebula> MATCH (a:player)-[r]->() \
  10.         WHERE id(a) == "player100" \
  11.         RETURN labels(a),  keys(r);
  12. +------------+----------------------------+
  13. | labels(a)  | keys(r)                    |
  14. +------------+----------------------------+
  15. | ["player"] | ["degree"]                 |
  16. +------------+----------------------------+
  17. | ["player"] | ["degree"]                 |
  18. +------------+----------------------------+
  19. | ["player"] | ["end_year", "start_year"] |
  20. +------------+----------------------------+
  22. nebula> MATCH p = (a:player)-[]->(b)-[]->(c:team) \
  23.         WHERE a.name == "Tim Duncan" AND c.name == "Spurs" \
  24.         RETURN nodes(p);
  25. +-----------------------------------------------------------------------------------------------------------------------------------------------+
  26. | nodes(p)                                                                                                                                      |
  27. +-----------------------------------------------------------------------------------------------------------------------------------------------+
  28. | [("player100" :player{age: 42, name: "Tim Duncan"}), ("player101" :player{age: 36, name: "Tony Parker"}), ("team204" :team{name: "Spurs"})]   |
  29. +-----------------------------------------------------------------------------------------------------------------------------------------------+
  30. | [("player100" :player{age: 42, name: "Tim Duncan"}), ("player125" :player{age: 41, name: "Manu Ginobili"}), ("team204" :team{name: "Spurs"})] |
  31. +-----------------------------------------------------------------------------------------------------------------------------------------------+
  33. nebula> MATCH p = (a:player)-[]->(b)-[]->(c:team) WHERE a.name == "Tim Duncan" AND c.name == "Spurs" RETURN relationships(p)
  34. +-----------------------------------------------------------------------------------------------------------------------------+
  35. | relationships(p)                                                                                                            |
  36. +-----------------------------------------------------------------------------------------------------------------------------+
  37. | [[:follow "player100"->"player101" @0 {degree: 95}], [:serve "player101"->"team204" @0 {end_year: 2018, start_year: 1999}]] |
  38. +-----------------------------------------------------------------------------------------------------------------------------+
  39. | [[:follow "player100"->"player125" @0 {degree: 95}], [:serve "player125"->"team204" @0 {end_year: 2018, start_year: 2002}]] |
  40. +-----------------------------------------------------------------------------------------------------------------------------+