我想用 postgis 分割线串。
我的功能:
@distance_b_to_a = Track.find_by_sql(
["SELECT
ST_Split(line, ST_Closestpoint(pta,line)) AS dst_line
FROM (
SELECT
'SRID=4326;LINESTRING(1.391991 46.441430,1.506078 46.556788)'::geometry line,
'SRID=4326;POINT(1.396636962890625 46.442352066959174)'::geometry pta,
) data"
])
还有我的节目:
<p>Test : <%= @distance_b_to_a.first.dst_line %></p>
返回我原来的线串:
Test : GEOMETRYCOLLECTION (LINESTRING (1.391991 46.44143, 1.506078 46.556788))
怎么了?
最佳答案
ST_Split
返回通过拆分几何图形产生的几何图形集合,所以恐怕这是预期的结果,因为您的 LineString
只有两个点。
考虑以下 LineString
...
LINESTRING(18.6435 42.5412,18.8440 42.5453,18.846 42.3994)
.. 并运行此查询,该查询使用上述 LineString
中的第二点应用 ST_Split
:
WITH j AS (
SELECT
'SRID=4326;POINT(18.8440 42.5453)'::GEOMETRY AS pta,
'SRID=4326;LINESTRING(18.6435 42.5412,18.8440 42.5453,18.846 42.3994)'::GEOMETRY AS line
)
SELECT
ST_AsText(
ST_Split(line,
ST_ClosestPoint(pta,line))) FROM j
...返回带有两个 LineStrings
的 GeometryCollection
:
st_astext
----------------------------------------------------------------------------------------------------------
GEOMETRYCOLLECTION(LINESTRING(18.6435 42.5412,18.844 42.5453),LINESTRING(18.844 42.5453,18.846 42.3994))
(1 Zeile)
关于ruby-on-rails - st_split 返回原始行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/50775980/