版本：0.10

地理函数

这个页面列出了 GreptimeDB 中的所有地理空间相关函数。当您启用了 common-function/geo 特性（默认为开启状态）时，这些函数才会生效。

Geo 数据类型函数

地理相关数据类型转换。

`wkt_point_from_latlng`

将纬度、经度转换成 WKT 点。

SELECT wkt_point_from_latlng(37.76938, -122.3889) AS point;

Geohash

了解更多关于 geohash 编码。

`geohash`

从纬度、经度和分辨率获取 geohash 编码的字符串。

SELECT geohash(37.76938, -122.3889, 11);

`geohash_neighbours`

给定坐标和分辨率获取所有 geohash 邻接点。

请注意，此函数返回一个字符串数组，并且仅在我们的HTTP查询API和Postgres通道上生效。

SELECT geohash_neighbours(37.76938, -122.3889, 11);

H3

H3 地理坐标编码算法。了解更多。

`h3_latlng_to_cell`

将坐标（纬度，经度）编码为指定分辨率下的 h3 索引，并返回该单元格的 UInt64 表示。

SELECT h3_latlng_to_cell(37.76938, -122.3889, 1);

`h3_latlng_to_cell_string`

类似于 h3_latlng_to_cell ，但返回字符串编码格式。

h3_latlng_to_cell_string(37.76938, -122.3889, 1);

`h3_cell_to_string`

将单元格索引（UInt64）转换为其字符串表示形式。

SELECT h3_cell_to_string(h3_latlng_to_cell(37.76938, -122.3889, 8));

`h3_string_to_cell`

将十六进制编码的单元 ID 转换为其 UInt64 形式。

h3_string_to_cell(h3_latlng_to_cell_string(37.76938, -122.3889, 8::UInt64));

`h3_cell_center_latlng`

返回单元中心的纬度和经度。

请注意，此函数返回一个浮点数数组，并且仅在我们的 HTTP 查询 API 和 Postgres 通道上有效。

SELECT h3_cell_center_latlng(h3_latlng_to_cell(37.76938, -122.3889, 8));

`h3_cell_resolution`

给定单元格的返回分辨率。

SELECT h3_cell_resolution(h3_latlng_to_cell(37.76938, -122.3889, 8));

`h3_cell_base`

返回给定单元的 Base 单元。

SELECT h3_cell_base(h3_latlng_to_cell(37.76938, -122.3889, 8));

`h3_cell_is_pentagon`

如果单元格是五边形，则返回 true。

SELECT h3_cell_is_pentagon(h3_latlng_to_cell(37.76938, -122.3889, 8));

`h3_cell_parent`

返回给定分辨率下单元的父单元。

h3_cell_parent(h3_latlng_to_cell(37.76938, -122.3889, 8), 6);

`h3_cell_to_children`

根据给定的分辨率返回子单元格。

请注意，此函数返回一个 UInt64 数组，并且仅在我们的 HTTP 查询 API 和 Postgres 通道上生效。

h3_cell_to_children(h3_latlng_to_cell(37.76938, -122.3889, 8), 10);

`h3_cell_to_children_size`

根据给定的分辨率，返回单元格中的子单元数量。

h3_cell_to_children_size(h3_latlng_to_cell(37.76938, -122.3889, 8), 10);

`h3_cell_to_child_pos`

根据给定分辨率，返回单元在其父单元的位置。位置是单元在所有子单元中的索引。

h3_cell_to_child_pos(h3_latlng_to_cell(37.76938, -122.3889, 8), 6)

`h3_child_pos_to_cell`

在给定分辨率下，返回父单元中给定位置的单元。

参数：

位置
单元索引
分辨率

h3_child_pos_to_cell(25, h3_latlng_to_cell(37.76938, -122.3889, 8), 11);

`h3_cells_contains`

测试输入的单元集合是否包含指定的单元，或其父单元。

参数：

单元集合：可以是 int64/uint64/string 数组, 或逗号分割的字符串单元 ID
单元索引

SELECT
    h3_cells_contains('86283470fffffff,862834777ffffff, 862834757ffffff, 86283471fffffff, 862834707ffffff', '8b283470d112fff') AS R00,
    h3_cells_contains(['86283470fffffff', '862834777ffffff', '862834757ffffff', '86283471fffffff', '862834707ffffff'], '8b283470d112fff') AS R11,
    h3_cells_contains([604189641255419903, 604189643000250367, 604189642463379455, 604189641523855359, 604189641121202175], 604189641792290815) AS R21;

`h3_grid_disk`

返回给定单元格的 k 个距离对应的单元格。

请注意，此函数返回一个 UInt64 数组，并且仅能在我们的 HTTP 查询 API 和 Postgres 通道上工作。

h3_grid_disk(h3_latlng_to_cell(37.76938, -122.3889, 8), 3);

`h3_grid_disk_distances`

返回给定单元格范围内所有距离为 k 的单元格。

请注意，此函数返回一个 UInt64 数组，并且仅适用于我们的 HTTP 查询 API 和 Postgres 通道。

h3_grid_disk_distance(h3_latlng_to_cell(37.76938, -122.3889, 8), 3);

`h3_grid_distance`

返回两单元的距离。

SELECT
    h3_grid_distance(cell1, cell2) AS distance,
FROM
    (
      SELECT
          h3_latlng_to_cell(37.76938, -122.3889, 8) AS cell1,
          h3_latlng_to_cell(39.634, -104.999, 8) AS cell2
    );

`h3_grid_path_cells`

此函数可在两个单元格之间返回路径单元格。请注意，如果两个单元格相距很远，该函数可能会失败。

SELECT
    h3_grid_path_cells(cell1, cell2) AS path_cells,
FROM
    (
      SELECT
          h3_latlng_to_cell(37.76938, -122.3889, 8) AS cell1,
          h3_latlng_to_cell(39.634, -104.999, 8) AS cell2
    );

`h3_distance_sphere_km`

返回两个单元中心的大圆距离，单位：千米

SELECT
    round(h3_distance_sphere_km(cell1, cell2), 5) AS sphere_distance
FROM
    (
      SELECT
          h3_string_to_cell('86283082fffffff') AS cell1,
          h3_string_to_cell('86283470fffffff') AS cell2
    );

`h3_distance_degree`

返回两个单元中心的欧式距离，单位：度

SELECT
    round(h3_distance_degree(cell1, cell2), 14) AS euclidean_distance
FROM
    (
      SELECT
          h3_string_to_cell('86283082fffffff') AS cell1,
          h3_string_to_cell('86283470fffffff') AS cell2
    );

S2

了解更多关于 S2 编码的信息.

`s2_latlng_to_cell`

给定坐标对应的 s2 单元索引。

SELECT s2_latlng_to_cell(37.76938, -122.3889);

`s2_cell_to_token`

给定单元格的字符串表示形式。

SELECT s2_cell_to_token(s2_latlng_to_cell(37.76938, -122.3889));

`s2_cell_level`

返回给定单元格的级别。

SELECT s2_cell_level(s2_latlng_to_cell(37.76938, -122.3889));

`s2_cell_parent`

返回给定单元格位于特定级别的父单元。

SELECT s2_cell_parent(s2_latlng_to_cell(37.76938, -122.3889), 3);

编码

`json_encode_path`

将纬度、经度按时间戳排序并编码为一个 JSON 数组。

参数：

纬度
经度
时间戳

返回一个字符串类型的JSON数组。请注意，结果坐标中的顺序为 [经度, 纬度]，以符合 GeoJSON 规范。

SELECT json_encode_path(lat, lon, ts);

示例输出：

[[-122.3888,37.77001],[-122.3839,37.76928],[-122.3889,37.76938],[-122.382,37.7693]]

空间关系

`st_contains`

测试两个空间对象是否为包含关系。

参数：WKT 编码的地理对象。

SELECT
    st_contains(polygon1, p1),
    st_contains(polygon2, p1),
FROM
    (
        SELECT
            wkt_point_from_latlng(37.383287, -122.01325) AS p1,
            'POLYGON ((-122.031661 37.428252, -122.139829 37.387072, -122.135365 37.361971, -122.057759 37.332222, -121.987707 37.328946, -121.943754 37.333041, -121.919373 37.349145, -121.945814 37.376705, -121.975689 37.417345, -121.998696 37.409164, -122.031661 37.428252))' AS polygon1,
            'POLYGON ((-121.491698 38.653343, -121.582353 38.556757, -121.469721 38.449287, -121.315883 38.541721, -121.491698 38.653343))' AS polygon2,
    );

`st_within`

测试两个空间对象是否为被包含关系。

参数：WKT 编码的地理对象。

SELECT
    st_within(p1, polygon1),
    st_within(p1, polygon2),
 ROM
    (
        SELECT
            wkt_point_from_latlng(37.383287, -122.01325) AS p1,
            'POLYGON ((-122.031661 37.428252, -122.139829 37.387072, -122.135365 37.361971, -122.057759 37.332222, -121.987707 37.328946, -121.943754 37.333041, -121.919373 37.349145, -121.945814 37.376705, -121.975689 37.417345, -121.998696 37.409164, -122.031661 37.428252))' AS polygon1,
            'POLYGON ((-121.491698 38.653343, -121.582353 38.556757, -121.469721 38.449287, -121.315883 38.541721, -121.491698 38.653343))' AS polygon2,
    );

`st_intersects`

测试两个空间对象是否为重叠关系。

参数：WKT 编码的地理对象。

SELECT
    st_intersects(polygon1, polygon2),
    st_intersects(polygon1, polygon3),
FROM
    (
        SELECT
            'POLYGON ((-122.031661 37.428252, -122.139829 37.387072, -122.135365 37.361971, -122.057759 37.332222, -121.987707 37.328946, -121.943754 37.333041, -121.919373 37.349145, -121.945814 37.376705, -121.975689 37.417345, -121.998696 37.409164, -122.031661 37.428252))' AS polygon1,
            'POLYGON ((-121.491698 38.653343, -121.582353 38.556757, -121.469721 38.449287, -121.315883 38.541721, -121.491698 38.653343))' AS polygon2,
            'POLYGON ((-122.089628 37.450332, -122.20535 37.378342, -122.093062 37.36088, -122.044301 37.372886, -122.089628 37.450332))' AS polygon3,
    );

Spatial Measurement

`st_distance`

返回两个对象的在 WGS84 坐标系下的欧式距离，单位：度。

参数：WKT 编码的地理对象。

SELECT
    st_distance(p1, p2) AS euclidean_dist,
    st_distance(p1, polygon1) AS euclidean_dist_pp,
FROM
    (
        SELECT
            wkt_point_from_latlng(37.76938, -122.3889) AS p1,
            wkt_point_from_latlng(38.5216, -121.4247) AS p2,
            'POLYGON ((-121.491698 38.653343, -121.582353 38.556757, -121.469721 38.449287, -121.315883 38.541721, -121.491698 38.653343))' AS polygon1,
    );

`st_distance_sphere_m`

返回两点的大圆距离，单位：米。

参数：WKT 编码的地理对象。

SELECT
    st_distance_sphere_m(p1, p2) AS sphere_dist_m,
FROM
    (
        SELECT
            wkt_point_from_latlng(37.76938, -122.3889) AS p1,
            wkt_point_from_latlng(38.5216, -121.4247) AS p2,
    );

`st_area`

返回地理对象的面积。

参数：WKT 编码的地理对象。

SELECT
    st_area(p1) as area_point,
    st_area(polygon1) as area_polygon,
FROM
    (
        SELECT
            wkt_point_from_latlng(37.76938, -122.3889) AS p1,
            'POLYGON ((-121.491698 38.653343, -121.582353 38.556757, -121.469721 38.449287, -121.315883 38.541721, -121.491698 38.653343))' AS polygon1,
    );

地理函数

Geo 数据类型函数​

wkt_point_from_latlng​

Geohash​

geohash​

geohash_neighbours​

H3​

h3_latlng_to_cell​

h3_latlng_to_cell_string​

h3_cell_to_string​

h3_string_to_cell​

h3_cell_center_latlng​

h3_cell_resolution​

h3_cell_base​

h3_cell_is_pentagon​

h3_cell_parent​

h3_cell_to_children​

h3_cell_to_children_size​

h3_cell_to_child_pos​

h3_child_pos_to_cell​

h3_cells_contains​

h3_grid_disk​

h3_grid_disk_distances​

h3_grid_distance​

h3_grid_path_cells​

h3_distance_sphere_km​

h3_distance_degree​

S2​

s2_latlng_to_cell​

s2_cell_to_token​

s2_cell_level​

s2_cell_parent​

编码​

json_encode_path​

空间关系​

st_contains​

st_within​

st_intersects​

Spatial Measurement​

st_distance​

st_distance_sphere_m​

st_area​

Geo 数据类型函数

`wkt_point_from_latlng`

Geohash

`geohash`

`geohash_neighbours`

H3

`h3_latlng_to_cell`

`h3_latlng_to_cell_string`

`h3_cell_to_string`

`h3_string_to_cell`

`h3_cell_center_latlng`

`h3_cell_resolution`

`h3_cell_base`

`h3_cell_is_pentagon`

`h3_cell_parent`

`h3_cell_to_children`

`h3_cell_to_children_size`

`h3_cell_to_child_pos`

`h3_child_pos_to_cell`

`h3_cells_contains`

`h3_grid_disk`

`h3_grid_disk_distances`

`h3_grid_distance`

`h3_grid_path_cells`

`h3_distance_sphere_km`

`h3_distance_degree`

S2

`s2_latlng_to_cell`

`s2_cell_to_token`

`s2_cell_level`

`s2_cell_parent`

编码

`json_encode_path`

空间关系

`st_contains`

`st_within`

`st_intersects`

Spatial Measurement

`st_distance`

`st_distance_sphere_m`

`st_area`