ST_LineLocatePoint takes a linestring column and a point column and returns a float column. The output column represents
the fractional distance along the linestring where it intersects the point. If the point does not
intersect the linestring, the function returns null. This function always returns null for multipart linestrings.
This function uses planar distance calculations.
| Function | Syntax |
|---|---|
| Python | line |
| SQL | ST |
| Scala | line |
For more details, go to the GeoAnalytics Engine API reference for line_locate_point.
Examples
from geoanalytics.sql import functions as ST
from pyspark.sql import functions as F
data = [
("LINESTRING (-117.27 34.05, -117.22 33.91, -116.96 33.64)",),
("LINESTRING (-116.89 33.96, -116.71 34.01, -116.66 34.08)",),
("LINESTRING (-116.24 33.88, -116.33 34.02)",)
]
df = spark.createDataFrame(data, ["line_wkt",]) \
.withColumn("linestring", ST.line_from_text("line_wkt", srid=4326)) \
.withColumn("point", ST.point_n("linestring", 1)) \
.withColumn("line_locate_point", ST.line_locate_point("linestring", "point"))
df.select(F.round("line_locate_point", 3).alias("line_locate_point")).show()Result
+-----------------+
|line_locate_point|
+-----------------+
| 0.284|
| 0.685|
| 1.0|
+-----------------+Version table
| Release | Notes |
|---|---|
1.6.0 | Python, SQL, and Scala functions introduced |