TRK_Between takes a track column and two offsets and returns a track. The result is the subset of the input track that comes between the two offset distances or offset durations. You can also use one offset distance and one offset duration.
An offset column can be created with ST_CreateDistance or
ST_CreateDuration. You can also define an offset with a tuple
containing a number and a unit string (e.g., (10, "kilometers") or (5, "minutes")).
For example, if you use a start distance offset of 2 miles and an end distance offset of 6 miles, the result track will be the subset of the input track that is between 2 and 6 miles along the input track's length from its start.
Similarly, if you use a start duration offset of 10 minutes and an end duration offset of 15 minutes, the result track will be the subset of the input track that is between 10 and 15 minutes from its start time.
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 | between(track, start |
| SQL | TRK |
For more details, go to the GeoAnalytics Engine API reference for between.
Examples
from geoanalytics.sql import functions as ST
from geoanalytics.tracks import functions as TRK
data = [
("LINESTRING M (-117.27 34.05 1633455010, -117.22 33.91 1633456062, -116.96 33.64 1633457132)",),
("LINESTRING M (-116.89 33.96 1633575895, -116.71 34.01 1633576982, -116.66 34.08 1633577061)",),
("LINESTRING M (-116.24 33.88 1633575234, -116.33 34.02 1633576336)",)
]
df = spark.createDataFrame(data, ["wkt"]).withColumn("track", ST.line_from_text("wkt", srid=4326)) \
.withColumn("5_minutes", TRK.query("track", (5, "minutes"))) \
.withColumn("15_minutes", TRK.query("track", (15, "minutes"))) \
.withColumn("start_point", ST.start_point("track")) \
.withColumn("end_point", ST.end_point("track"))
result = df.withColumn("between", TRK.between("track", (5, "minutes"), (15, "minutes")))
ax = result.st.plot("track", edgecolor="lightgrey", linewidths=10, zorder=0, figsize=(15, 8))
result.st.plot("start_point", ax=ax, s=75, facecolor="green", zorder=2)
result.st.plot("end_point", ax=ax, s=75, facecolor="red", zorder=2)
result.st.plot("5_minutes", ax=ax, s=75, facecolor="black", marker="x", zorder=2)
result.st.plot("15_minutes", ax=ax, s=75, facecolor="black", marker="X", zorder=2)
result.st.plot("between", ax=ax, edgecolor="greenyellow", linewidths=3, zorder=1)
ax.legend(['Input track','Input track start','Input track end','5 minutes along input track',
'15 minutes along input track','Result track'], loc='lower right', fontsize='x-large')
Version table
| Release | Notes |
|---|---|
1.4.0 | Function introduced |