ST_LineInterpolatePoint

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from geoanalytics.sql import functions as ST

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("line_interpolate_point", ST.line_interpolate_point("linestring", 0.25))

ax = df.st.plot("linestring", edgecolor="lightgrey", zorder=0, linewidths=10, figsize=(15, 8))
df.st.plot("line_interpolate_point", ax=ax, facecolor="red", s=75, zorder=1)
ax.legend(['Input linestring','Point 25% along linestring'], loc='lower right', fontsize='x-large')

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import com.esri.geoanalytics.sql.{functions => ST}
import org.apache.spark.sql.{functions => F}

case class lineRow(lineWkt: String)

val data = Seq(lineRow("LINESTRING (-117.27 34.05, -117.22 33.91, -116.96 33.64)"),
               lineRow("LINESTRING (-116.89 33.96, -116.71 34.01, -116.66 34.08)"),
               lineRow("LINESTRING (-116.24 33.88, -116.33 34.02)"))

val df = spark.createDataFrame(data)
              .withColumn("linestring", ST.lineFromText($"lineWkt", F.lit(4326)))
              .withColumn("line_interpolate_point", ST.lineInterpolatePoint($"linestring", F.lit(0.25)))

df.select("line_interpolate_point").show(truncate = false)

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+------------------------------------------------+
|line_interpolate_point                          |
+------------------------------------------------+
|{"x":-117.22598247991357,"y":33.92675094375801} |
|{"x":-116.82427876385185,"y":33.97825589893004} |
|{"x":-116.26249999999999,"y":33.915000000000006}|
+------------------------------------------------+