Magellen: Geospatial Analytics on Spark by Ram Sriharsha

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Magellan: Geospatial Analytics on Spark
Ram Sriharsha
Spark and Data Science Architect,
Hortonworks

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What is geospatial context?
•Given a point = (-122.412651, 37.777748) which
city is it in?
•Does shape X intersect shape Y?
–Compute the intersection
•Given a sequence of points and a system of roads
–Compute best path representing points

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Geospatial context is useful
What neighborhoods do people go to on weekends?
Predict the drop off neighborhood of a user?
Predict the location where next pick up can be expected?
How does usage pattern change with time?
Identify crime hotspot neighborhoods
How do these hotspots evolve with time?
Predict the likelihood of crime occurring at a given neighborhood
Predict climate at fairly granular level
Climate insurance: do I need to buy insurance for my crops?
Climate as a factor in crime: Join climate dataset with Crimes

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Geospatial data is pervasive

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Why geospatial now?
Vast mobile data + geospatial
= truly big data problem !

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Do you think we need one more geospatial library?

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Ancient data formats

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Coordinate System Hell!
Mobile data = GPS coordinates
Map coordinate systems optimized for precision
⇒Transform from one to another
No good transformation libraries

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Simple, intuitive,
handles common
formats
Scalable
Feature rich
but still
extensible
Venn Diagram of geospatial libraries?

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Feature Extractors
Language integration simplifies exploratory analytics
Q-Q
Q-A
similarity
Parse +
Clean
Logs
Ad
category
mapping
Query
category
mapping
Poly
Exp
(Q-A)
Features
Model
Convex
Solver
Train/T
est
Split
train
Test/validation
Metrics
Ad Server
HDFS
Data Prep
Score Model - Real-time
Data
Flow
Stage
Data Flow Stage - Batch
Feedback
Spatial
Context

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Not all is lost!
• local computations w/ ESRI Java API
• Scale out computation w/ Spark
• Python + R support without compromising
performance via Pyspark , SparkR
• Catalyst + Data Sources + Data Frames
= Flexibility + Simplicity + Performance
• Stitch it all together + Allow extension points
=> Success!

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Magellan: a complete story for geospatial?
Create geospatial analytics applications
faster:
• Use your favorite language (Python/ Scala), even R
• Get best in class algorithms for common spatial analytics
• Write less code
• Read data efficiently
• Let the optimizer do the heavy lifting

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How does it work?
Custom Data Types for Shapes:
• Point, Line, PolyLine, Polygon extend Shape
• Local Computations using ESRI Java API
• No need for Scala -> SQL serialization
Expressions for Operators:
• Literals e.g point(-122.4, 37.6)
• Boolean Expressions e.g Intersects, Contains
• Binary Expressions e.g Intersection
Custom Data Sources:
• Schema = [point, polyline, polygon, metadata]
• Metadata = Map[String, String]
• GeoJSON and Shapefile implementations
Custom Strategies for Spatial Join:
• Broadcast Cartesian Join
• Geohash Join (in progress)
• Plug into Catalyst as experimental strategies

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Magellan in a nutshell
• Read Shapefiles/ GeoJSON as DataSources:
–sqlContext.read("magellan").load(“$path”)
–sqlContext.read(“magellan”).option(“type”, “geojson”).load(“$path”)
• Spatial Queries using Expressions
–point(-122.5, 37.6) = Shape Literal
–$”point” within $”polygon” = Boolean Expression
–$”polygon1” intersection $”polygon2” = Binary Expression
• Joins using Catalyst + Spatial Optimizations
–points.join(polygons).where($”point” within $”polygon”)

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Where are we at?
Magellan 1.0.3 is out on Spark Packages, go give it a try!:
• Scala support, Python support will be functional in 1.0.4 (needs Spark 1.5)
• Github: https://github.com/harsha2010/magellan
• Spark Packages: http://spark-packages.org/package/harsha2010/magellan
• Data Formats: ESRI Shapefile + metadata, GeoJSON
• Operators: Intersects, Contains, Within, Intersection
• Joins: Broadcast
• Blog: http://hortonworks.com/blog/magellan-geospatial-analytics-in-spark/
• Zeppelin Notebook Example: http://bit.ly/1kvwGjC

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What is next?
Magellan 1.0.4 expected release December:
• Python support
• MultiPolygon (Polygon Collection), MultiLineString (PolyLine Collection)
• Spark 1.5, 1.6
• Spatial Join Optimization
• Map Matching Algorithms
• More Operators based on requirements
• Support for other common geospatial data formats (WKT, others?)

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Demo
Reading Geospatial Formats
Uber queries