TRK_IsValid takes a linestring column and returns a boolean column where True indicates that a linestring is
a valid track and False indicates that a linestring is not a valid track.
A linestring is considered a valid track if all of the following criteria are met:
- The linestring is not null.
- The linestring is not empty.
- The linestring has M-values that are distinct and increasing.
Tracks are linestrings that represent the change in an entity's location over time. Each vertex in the linestring has a timestamp (stored as the M-value) and the vertices are ordered sequentially.
For more information on using tracks in GeoAnalytics Engine, see the core concept topic on tracks.
| Function | Syntax |
|---|---|
| Python | is |
| SQL | TRK |
For more details, go to the GeoAnalytics Engine API reference for is_valid.
Examples
from geoanalytics.tracks import functions as TRK
from geoanalytics.sql import functions as ST
data = [
("LINESTRING M (-117.27 34.05 1633455010, -117.22 33.91 1633456062)",),
("LINESTRING (-116.89 33.96, -116.71 34.01, -116.66 34.08)",),
("LINESTRING M EMPTY",)
]
df = spark.createDataFrame(data, ["wkt",]) \
.withColumn("track", ST.line_from_text("wkt", srid=4326))
df.select("track", TRK.is_valid("track").alias("is_valid")).show(truncate=False)
Result
+------------------------------------------------------------------------------------+--------+
|track |is_valid|
+------------------------------------------------------------------------------------+--------+
|{"hasM":true,"paths":[[[-117.27,34.05,1.63345501e9],[-117.22,33.91,1.633456062e9]]]}|true |
|{"paths":[[[-116.89,33.96],[-116.71,34.01],[-116.66,34.08]]]} |false |
|{"hasM":true,"paths":[]} |false |
+------------------------------------------------------------------------------------+--------+Version table
| Release | Notes |
|---|---|
1.4.0 | Function introduced |