Create H3 hexagons Mosaic

shanakap — Wed, 14 Sep 2022 08:32:46 GMT

I am new to using `Mosaic` on Databricks. The task is to create a Heatmap with the counts within Hexagons of H3 resolution. Since the dataset is quite large I am opting for Mosaic. As the first step I am trying to create the hexagons covering the given area but the following code does not generate hexagons covering the full square as illustrated below:

from pyspark.sql.functions import *
from mosaic import enable_mosaic
enable_mosaic(spark, dbutils)
 
from pyspark import SparkContext
from pyspark.sql import functions as F
import mosaic as mos
 
 
from mosaic import st_point
 
lons = [-80., -80., -70., -70., -80.]
lats = [ 35.,  45.,  45.,  35.,  35.]
 
bounds_df = (
  spark
  .createDataFrame({"lon": lon, "lat": lat} for lon, lat in zip(lons, lats))
  .coalesce(1)
  .withColumn("point_geom", st_point("lon", "lat"))
)
bounds_df.show()
 
from mosaic import st_makeline
 
bounds_df = (
  bounds_df
  .groupBy()
  .agg(F.collect_list("point_geom").alias("bounding_coords"))
  .select(st_makeline("bounding_coords").alias("bounding_ring"))
)
bounds_df.show()
 
from mosaic import st_makepolygon
 
bounds_df = bounds_df.select(st_makepolygon("bounding_ring").alias("bounds"))
bounds_df.show()
 
 
hexs = (bounds_df
       .select(mos.mosaic_explode("bounds", lit(5)))
       .select("index.*")
    )
 
hexs.show()
 
%%mosaic_kepler
hexs "index_id" "h3"

Do you know why there are gaps between the hexagons?

Re: Create H3 hexagons Mosaic

shanakap — Thu, 15 Sep 2022 08:40:05 GMT

This only shows a sample, hence the gap between the hexagons.

Re: Create H3 hexagons Mosaic

Anonymous — Wed, 28 Sep 2022 07:08:18 GMT

Hi @Shanaka Pererea

Hope all is well! Just wanted to check in if you were able to resolve your issue and would you be happy to share the solution or mark an answer as best? Else please let us know if you need more help.

We'd love to hear from you.

Thanks!

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Create H3 hexagons Mosaic

Re: Create H3 hexagons Mosaic

Re: Create H3 hexagons Mosaic