Name
ST_EndM — Returns the M coordinate of the last point of a LineString, CircularLineString, or NURBSCurve.
Synopsis
float8 ST_EndM(geometry geom);
描述
Returns the M coordinate of the last point of a LINESTRING, CIRCULARLINESTRING, or NURBSCURVE geometry. Returns NULL if the input geometry does not have an M dimension or is not a LINESTRING, CIRCULARLINESTRING, or NURBSCURVE.
此方法支持圆形字符串和曲线。
示例
End M value of a LineString
SELECT ST_EndM('LINESTRING M(0 0 10, 1 1 20, 2 0 30)'::geometry);
st_endm
---------
30
End M value of a CircularString
SELECT ST_EndM('CIRCULARSTRING M(0 0 5, 1 1 10, 2 0 15)'::geometry);
st_endm
---------
15
End M value of a NURBSCurve
SELECT ST_EndM('NURBSCURVE M(2, (0 0 100, 1 1 200, 2 0 300))'::geometry);
st_endm
---------
300
Geometry without M dimension returns NULL
SELECT ST_EndM('LINESTRING(0 0, 1 1)'::geometry) IS NULL AS is_null;
is_null
---------
t