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add geo #1081

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add geo
cooper-lzy committed Oct 21, 2021

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commit 31027f80d9633c6b3116bc1a7f756f649c1ac267
74 changes: 74 additions & 0 deletions docs-2.0/3.ngql-guide/3.data-types/10.geography.md
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# 地理位置

地理位置(GEOGRAPHY)是表示地理空间信息的数据类型。Nebula Graph当前支持部分WKT(Well-Know-Text)标准的数据类型,通过函数将地理空间信息数据转化为WKB(Well-Know-Binary)标准的二进制序列进行存储。

## GEOGRAPHY

|类型|示例|说明|
|:--|:--|:--|
|Point|`"POINT(3 8)"`|点类型|
|LineString|`"LINESTRING(3 8, 4.7 73.23)"`|线段类型|
|Polygon|`"POLYGON((0 1, 1 2, 2 3, 0 1))"`|多边形类型|

<!--
## 索引

为GEOGRAPHY类型数据创建索引时,支持指定[S2单元](https://s2geometry.io/devguide/s2cell_hierarchy)覆盖选项。

```ngql
CREATE TAG INDEX <index_name> ON <tag_name>(<geo_prop_name>) s2_min_level = <int>, s2_max_level = <int>, s2_max_cells = <int>;
```
-->

## 示例

geo相关函数请参见[geo函数](../6.functions-and-expressions/14.geo.md)。

```ngql
//创建Tag,支持任意形状地理位置数据类型。
nebula> CREATE TAG any_shape(geo geography);

//创建Tag,仅支持点形状地理位置数据类型。
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nebula> CREATE TAG only_point(geo geography(point));

//创建Tag,仅支持线段形状地理位置数据类型。
nebula> CREATE TAG only_linestring(geo geography(linestring));

//创建Tag,仅支持多边形形状地理位置数据类型。
nebula> CREATE TAG only_polygon(geo geography(polygon));

//创建Edge type,支持任意形状地理位置数据类型。
nebula> CREATE EDGE any_shape_edge(geo geography);

//创建存储多边形地理位置的点。
nebula> INSERT VERTEX any_shape(geo) VALUES "103":(ST_GeogFromText("POLYGON((0 1, 1 2, 2 3, 0 1))"));

//创建存储多边形地理位置的边。
nebula> INSERT EDGE any_shape_edge(geo) VALUES "201"->"302":(ST_GeogFromText("POLYGON((0 1, 1 2, 2 3, 0 1))"));

//查询点103的属性geo。
nebula> FETCH PROP ON any_shape "103" YIELD ST_ASText(any_shape.geo);
+----------+---------------------------------+
| VertexID | ST_ASText(any_shape.geo) |
+----------+---------------------------------+
| "103" | "POLYGON((0 1, 1 2, 2 3, 0 1))" |
+----------+---------------------------------+

//查询边201->302的属性geo。
nebula> FETCH PROP ON any_shape_edge "201"->"302" YIELD ST_ASText(any_shape_edge.geo);
+---------------------+---------------------+----------------------+---------------------------------+
| any_shape_edge._src | any_shape_edge._dst | any_shape_edge._rank | ST_ASText(any_shape_edge.geo) |
+---------------------+---------------------+----------------------+---------------------------------+
| "201" | "302" | 0 | "POLYGON((0 1, 1 2, 2 3, 0 1))" |
+---------------------+---------------------+----------------------+---------------------------------+

//为geo属性创建索引并使用LOOKUP查询。
nebula> CREATE TAG INDEX any_shape_geo_index ON any_shape(geo);
nebula> REBUILD TAG INDEX any_shape_geo_index;
nebula> LOOKUP ON any_shape YIELD ST_ASText(any_shape.geo);
+----------+-------------------------------------------------+
| VertexID | ST_ASText(any_shape.geo) |
+----------+-------------------------------------------------+
| "103" | "POLYGON((0 1, 1 2, 2 3, 0 1))" |
+----------+-------------------------------------------------+
```
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# geo函数

geo函数用于生成地理位置(GEOGRAPHY)数据类型的值或对其执行操作。

关于地理位置数据类型说明请参见[地理位置](../3.data-types/10.geography.md)。

## 函数说明

|函数| 说明 |
|:----|:----|
|GEOGRAPHY ST_Point(longitude, latitude) |创建包含一个点的地理位置。如需将GEOGRAPHY的格式设置为WKT,请使用`ST_ASText`。|
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|GEOGRAPHY ST_GeogFromText(wkt_string) |返回与传入的WKT字符串形式相对应的GEOGRAPHY。如需将GEOGRAPHY的格式设置为WKT,请使用`ST_ASText`。|
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|STRING ST_ASText(geography_expression) |返回传入的GEOGRAPHY的WKT字符串形式。|
|GEOGRAPHY ST_Centroid(geography_expression) |以单点GEOGRAPHY的形式返回传入的GEOGRAPHY的形心。|
|BOOL ST_ISValid(geography_expression) |返回传入的GEOGRAPHY是否有效。 |
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|BOOL ST_Intersects(geography_1, geography_2) |返回传入的两个GEOGRAPHY是否有交集。|
|BOOL ST_Covers(geography_1, geography_2) |返回geography_1是否完全包含geography_2。如果geography_2中没有位于geography_1外部的点,返回True。|
|BOOL ST_CoveredBy(geography_1, geography_2) |返回geography_2是否完全包含geography_1。如果geography_1中没有位于geography_2外部的点,返回True。|
|BOOL ST_DWithin(geography_1, geography_2, distance)|如果geography_1中至少有一个点与geography_2中的一个点的距离小于或等于distance参数(以米为单位)指定的距离,则返回True。 |
|FLOAT ST_Distance(geography_1, geography_2) |返回两个非空GEOGRAPHY之间的最短距离(以米为单位)。|
|INT S2_CellIdFromPoint(point_geography) |返回覆盖点GEOGRAPHY的[S2单元](https://s2geometry.io/devguide/s2cell_hierarchy)ID。|
|ARRAY<INT64> S2_CoveringCellIds(geography) |返回覆盖传入的GEOGRAPHY的S2单元ID的数组。|

## 示例

```ngql
nebula> RETURN ST_ASText(ST_Point(1,1))
+--------------------------+
| ST_ASText(ST_Point(1,1)) |
+--------------------------+
| "POINT(1 1)" |
+--------------------------+

nebula> RETURN ST_ASText(ST_GeogFromText("POINT(3 8)"));
+------------------------------------------+
| ST_ASText(ST_GeogFromText("POINT(3 8)")) |
+------------------------------------------+
| "POINT(3 8)" |
+------------------------------------------+

nebula> RETURN ST_ASTEXT(ST_Centroid(ST_GeogFromText("LineString(0 1,1 0)")));
+----------------------------------------------------------------+
| ST_ASTEXT(ST_Centroid(ST_GeogFromText("LineString(0 1,1 0)"))) |
+----------------------------------------------------------------+
| "POINT(0.5000380800773782 0.5000190382261059)" |
+----------------------------------------------------------------+

nebula> RETURN ST_ISValid(ST_GeogFromText("POINT(3 8)"));
+-------------------------------------------+
| ST_ISValid(ST_GeogFromText("POINT(3 8)")) |
+-------------------------------------------+
| true |
+-------------------------------------------+

nebula> RETURN ST_Intersects(ST_GeogFromText("LineString(0 1,1 0)"),ST_GeogFromText("LineString(0 0,1 1)"));
+----------------------------------------------------------------------------------------------+
| ST_Intersects(ST_GeogFromText("LineString(0 1,1 0)"),ST_GeogFromText("LineString(0 0,1 1)")) |
+----------------------------------------------------------------------------------------------+
| true |
+----------------------------------------------------------------------------------------------+

nebula> RETURN ST_Covers(ST_GeogFromText("POLYGON((0 0,10 0,10 10,0 10,0 0))"),ST_Point(1,2));
+--------------------------------------------------------------------------------+
| ST_Covers(ST_GeogFromText("POLYGON((0 0,10 0,10 10,0 10,0 0))"),ST_Point(1,2)) |
+--------------------------------------------------------------------------------+
| true |
+--------------------------------------------------------------------------------+

nebula> RETURN ST_CoveredBy(ST_Point(1,2),ST_GeogFromText("POLYGON((0 0,10 0,10 10,0 10,0 0))"));
+-----------------------------------------------------------------------------------+
| ST_CoveredBy(ST_Point(1,2),ST_GeogFromText("POLYGON((0 0,10 0,10 10,0 10,0 0))")) |
+-----------------------------------------------------------------------------------+
| true |
+-----------------------------------------------------------------------------------+

nebula> RETURN ST_dwithin(ST_GeogFromText("Point(0 0)"),ST_GeogFromText("Point(10 10)"),20000000000.0);
+---------------------------------------------------------------------------------------+
| ST_dwithin(ST_GeogFromText("Point(0 0)"),ST_GeogFromText("Point(10 10)"),20000000000) |
+---------------------------------------------------------------------------------------+
| true |
+---------------------------------------------------------------------------------------+

nebula> RETURN ST_Distance(ST_GeogFromText("Point(0 0)"),ST_GeogFromText("Point(10 10)"));
+----------------------------------------------------------------------------+
| ST_Distance(ST_GeogFromText("Point(0 0)"),ST_GeogFromText("Point(10 10)")) |
+----------------------------------------------------------------------------+
| 1568523.0187677438 |
+----------------------------------------------------------------------------+

nebula> RETURN S2_CellIdFromPoint(ST_GeogFromText("Point(1 1)"));
+---------------------------------------------------+
| S2_CellIdFromPoint(ST_GeogFromText("Point(1 1)")) |
+---------------------------------------------------+
| 1153277837650709461 |
+---------------------------------------------------+

nebula> RETURN S2_CoveringCellIds(ST_GeogFromText("POLYGON((0 1, 1 2, 2 3, 0 1))"));
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| S2_CoveringCellIds(ST_GeogFromText("POLYGON((0 1, 1 2, 2 3, 0 1))")) |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| [1152391494368201343, 1153466862374223872, 1153554823304445952, 1153836298281156608, 1153959443583467520, 1154240918560178176, 1160503736791990272, 1160591697722212352] |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
```