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Spark: Generating CSV Files to Import into Neo4j

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Spark: Generating CSV Files to Import into Neo4j

Using Neo4j and Spark, I used a Chicago Crime data set to generate a CSV file to be read and analyzed in an import to Neo4j.

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About a year ago Ian pointed me at a Chicago Crime data set which seemed like a good fit for Neo4j and after much procrastination I’ve finally got around to importing it.

The data set covers crimes committed from 2001 until now. It contains around 4 million crimes and meta data around those crimes such as the location, type of crime and year to name a few.

The contents of the file follow this structure:


$ head -n 10 ~/Downloads/Crimes_-_2001_to_present.csv
ID,Case Number,Date,Block,IUCR,Primary Type,Description,Location Description,Arrest,Domestic,Beat,District,Ward,Community Area,FBI Code,X Coordinate,Y Coordinate,Year,Updated On,Latitude,Longitude,Location
9464711,HX114160,01/14/2014 05:00:00 AM,028XX E 80TH ST,0560,ASSAULT,SIMPLE,APARTMENT,false,true,0422,004,7,46,08A,1196652,1852516,2014,01/20/2014 12:40:05 AM,41.75017626412204,-87.55494559131228,"(41.75017626412204, -87.55494559131228)"
9460704,HX113741,01/14/2014 04:55:00 AM,091XX S JEFFERY AVE,031A,ROBBERY,ARMED: HANDGUN,SIDEWALK,false,false,0413,004,8,48,03,1191060,1844959,2014,01/18/2014 12:39:56 AM,41.729576153145636,-87.57568059471686,"(41.729576153145636, -87.57568059471686)"
9460339,HX113740,01/14/2014 04:44:00 AM,040XX W MAYPOLE AVE,1310,CRIMINAL DAMAGE,TO PROPERTY,RESIDENCE,false,true,1114,011,28,26,14,1149075,1901099,2014,01/16/2014 12:40:00 AM,41.884543798701515,-87.72803579358926,"(41.884543798701515, -87.72803579358926)"
9461467,HX114463,01/14/2014 04:43:00 AM,059XX S CICERO AVE,0820,THEFT,$500 AND UNDER,PARKING LOT/GARAGE(NON.RESID.),false,false,0813,008,13,64,06,1145661,1865031,2014,01/16/2014 12:40:00 AM,41.785633535413176,-87.74148516669783,"(41.785633535413176, -87.74148516669783)"
9460355,HX113738,01/14/2014 04:21:00 AM,070XX S PEORIA ST,0820,THEFT,$500 AND UNDER,STREET,true,false,0733,007,17,68,06,1171480,1858195,2014,01/16/2014 12:40:00 AM,41.766348042591375,-87.64702037047671,"(41.766348042591375, -87.64702037047671)"
9461140,HX113909,01/14/2014 03:17:00 AM,016XX W HUBBARD ST,0610,BURGLARY,FORCIBLE ENTRY,COMMERCIAL / BUSINESS OFFICE,false,false,1215,012,27,24,05,1165029,1903111,2014,01/16/2014 12:40:00 AM,41.889741146006095,-87.66939334853973,"(41.889741146006095, -87.66939334853973)"
9460361,HX113731,01/14/2014 03:12:00 AM,022XX S WENTWORTH AVE,0820,THEFT,$500 AND UNDER,CTA TRAIN,false,false,0914,009,25,34,06,1175363,1889525,2014,01/20/2014 12:40:05 AM,41.85223460427207,-87.63185047834335,"(41.85223460427207, -87.63185047834335)"
9461691,HX114506,01/14/2014 03:00:00 AM,087XX S COLFAX AVE,0650,BURGLARY,HOME INVASION,RESIDENCE,false,false,0423,004,7,46,05,1195052,1847362,2014,01/17/2014 12:40:17 AM,41.73607283858007,-87.56097809501115,"(41.73607283858007, -87.56097809501115)"
9461792,HX114824,01/14/2014 03:00:00 AM,012XX S CALIFORNIA BLVD,0810,THEFT,OVER $500,STREET,false,false,1023,010,28,29,06,1157929,1894034,2014,01/17/2014 12:40:17 AM,41.86498077118534,-87.69571529596696,"(41.86498077118534, -87.69571529596696)"

Since I wanted to import this into Neo4j I needed to do some massaging of the data since the neo4j-import tool expects to receive CSV files containing the nodes and relationships we want to create.


Spark logo 192x100px

I’d been looking at Spark towards the end of last year and the pre-processing of the big initial file into smaller CSV files containing nodes and relationships seemed like a good fit.

I therefore needed to create a Spark job to do this. We’ll then pass this job to a Spark executor running locally and it will spit out CSV files.


2015 04 15 00 51 42

We start by creating a Scala object with a main method that will contain our processing code. Inside that main method we’ll instantiate a Spark context:


import org.apache.spark.{SparkConf, SparkContext}

object GenerateCSVFiles {  
    def main(args: Array[String]) {    
        val conf = new SparkConf().setAppName("Chicago Crime Dataset")    
        val sc = new SparkContext(conf)  
    }
}

Easy enough. Next we’ll read in the CSV file. I found the easiest way to reference this was with an environment variable but perhaps there’s a more idiomatic way:


import java.io.File
import org.apache.spark.{SparkConf, SparkContext}

object GenerateCSVFiles {
  def main(args: Array[String]) {
    var crimeFile = System.getenv("CSV_FILE")

    if(crimeFile == null || !new File(crimeFile).exists()) {
      throw new RuntimeException("Cannot find CSV file [" + crimeFile + "]")
    }

    println("Using %s".format(crimeFile))

    val conf = new SparkConf().setAppName("Chicago Crime Dataset")

    val sc = new SparkContext(conf)
    val crimeData = sc.textFile(crimeFile).cache()
}

The type of crimeData is RDD[String] – Spark’s way of representing the (lazily evaluated) lines of the CSV file. This also includes the header of the file so let’s write a function to get rid of that since we’ll be generating our own headers for the different files:


import org.apache.spark.rdd.RDD

// http://mail-archives.apache.org/mod_mbox/spark-user/201404.mbox/%3CCAEYYnxYuEaie518ODdn-fR7VvD39d71=CgB_Dxw_4COVXgmYYQ@mail.gmail.com%3E
def dropHeader(data: RDD[String]): RDD[String] = {
  data.mapPartitionsWithIndex((idx, lines) => {
    if (idx == 0) {
      lines.drop(1)
    }
    lines
  })
}

Now we’re ready to start generating our new CSV files so we’ll write a function which parses each line and extracts the appropriate columns. I’m using Open CSV for this:


import au.com.bytecode.opencsv.CSVParser

def generateFile(file: String, withoutHeader: RDD[String], fn: Array[String] => Array[String], header: String , distinct:Boolean = true, separator: String = ",") = {
  FileUtil.fullyDelete(new File(file))

  val tmpFile = "/tmp/" + System.currentTimeMillis() + "-" + file
  val rows: RDD[String] = withoutHeader.mapPartitions(lines => {
    val parser = new CSVParser(',')
    lines.map(line => {
      val columns = parser.parseLine(line)
      fn(columns).mkString(separator)
    })
  })

  if (distinct) rows.distinct() saveAsTextFile tmpFile else rows.saveAsTextFile(tmpFile)
}

We then call this function like this:


generateFile("/tmp/crimes.csv", withoutHeader, columns => Array(columns(0),"Crime", columns(2), columns(6)), "id:ID(Crime),:LABEL,date,description", false)

The output into ‘tmpFile’ is actually 32 ‘part files’ but I wanted to be able to merge those together into individual CSV files that were easier to work with.

I won’t paste the the full job here but if you want to take a look it’s on github.

Now we need to submit the job to Spark. I’ve wrapped this in a script if you want to follow along but these are the contents:


./spark-1.1.0-bin-hadoop1/bin/spark-submit \
--driver-memory 5g \
--class GenerateCSVFiles \
--master local[8] \ 
target/scala-2.10/playground_2.10-1.0.jar \
$@

If we execute that we’ll see the following output…”


Spark assembly has been built with Hive, including Datanucleus jars on classpath
Using Crimes_-_2001_to_present.csv
Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
15/04/15 00:31:44 INFO SparkContext: Running Spark version 1.3.0
...
15/04/15 00:47:26 INFO TaskSchedulerImpl: Removed TaskSet 8.0, whose tasks have all completed, from pool
15/04/15 00:47:26 INFO DAGScheduler: Stage 8 (saveAsTextFile at GenerateCSVFiles.scala:51) finished in 2.702 s
15/04/15 00:47:26 INFO DAGScheduler: Job 4 finished: saveAsTextFile at GenerateCSVFiles.scala:51, took 8.715588 s

real0m44.935s
user4m2.259s
sys0m14.159s

and these CSV files will be generated:


$ ls -alh /tmp/*.csv
-rwxrwxrwx  1 markneedham  wheel   3.0K 14 Apr 07:37 /tmp/beats.csv
-rwxrwxrwx  1 markneedham  wheel   217M 14 Apr 07:37 /tmp/crimes.csv
-rwxrwxrwx  1 markneedham  wheel    84M 14 Apr 07:37 /tmp/crimesBeats.csv
-rwxrwxrwx  1 markneedham  wheel   120M 14 Apr 07:37 /tmp/crimesPrimaryTypes.csv
-rwxrwxrwx  1 markneedham  wheel   912B 14 Apr 07:37 /tmp/primaryTypes.csv

Let’s have a quick check what they contain:


$ head -n 10 /tmp/beats.csv
id:ID(Beat),:LABEL
1135,Beat
1421,Beat
2312,Beat
1113,Beat
1014,Beat
2411,Beat
1333,Beat
2521,Beat
1652,Beat


$ head -n 10 /tmp/crimes.csv
id:ID(Crime),:LABEL,date,description
9464711,Crime,01/14/2014 05:00:00 AM,SIMPLE
9460704,Crime,01/14/2014 04:55:00 AM,ARMED: HANDGUN
9460339,Crime,01/14/2014 04:44:00 AM,TO PROPERTY
9461467,Crime,01/14/2014 04:43:00 AM,$500 AND UNDER
9460355,Crime,01/14/2014 04:21:00 AM,$500 AND UNDER
9461140,Crime,01/14/2014 03:17:00 AM,FORCIBLE ENTRY
9460361,Crime,01/14/2014 03:12:00 AM,$500 AND UNDER
9461691,Crime,01/14/2014 03:00:00 AM,HOME INVASION
9461792,Crime,01/14/2014 03:00:00 AM,OVER $500


$ head -n 10 /tmp/crimesBeats.csv
:START_ID(Crime),:END_ID(Beat),:TYPE
5896915,0733,ON_BEAT
9208776,2232,ON_BEAT
8237555,0111,ON_BEAT
6464775,0322,ON_BEAT
6468868,0411,ON_BEAT
4189649,0524,ON_BEAT
7620897,0421,ON_BEAT
7720402,0321,ON_BEAT
5053025,1115,ON_BEAT

Looking good. Let’s get them imported into Neo4j:


$ ./neo4j-community-2.2.0/bin/neo4j-import --into /tmp/my-neo --nodes /tmp/crimes.csv --nodes /tmp/beats.csv --nodes /tmp/primaryTypes.csv --relationships /tmp/crimesBeats.csv --relationships /tmp/crimesPrimaryTypes.csv
Nodes
[*>:45.76 MB/s----------------------------------|PROPERTIES(2)=============|NODE:3|v:118.05 MB/]  4M
Done in 5s 605ms
Prepare node index
[*RESOLVE:64.85 MB-----------------------------------------------------------------------------]  4M
Done in 4s 930ms
Calculate dense nodes
[>:42.33 MB/s-------------------|*PREPARE(7)===================================|CALCULATOR-----]  8M
Done in 5s 417ms
Relationships
[>:42.33 MB/s-------------|*PREPARE(7)==========================|RELATIONSHIP------------|v:44.]  8M
Done in 6s 62ms
Node --> Relationship
[*>:??-----------------------------------------------------------------------------------------]  4M
Done in 324ms
Relationship --> Relationship
[*LINK-----------------------------------------------------------------------------------------]  8M
Done in 1s 984ms
Node counts
[*>:??-----------------------------------------------------------------------------------------]  4M
Done in 360ms
Relationship counts
[*>:??-----------------------------------------------------------------------------------------]  8M
Done in 653ms

IMPORT DONE in 26s 517ms

Next I updated conf/neo4j-server.properties to point to my new database:


#***************************************************************
# Server configuration
#***************************************************************

# location of the database directory
#org.neo4j.server.database.location=data/graph.db
org.neo4j.server.database.location=/tmp/my-neo

Now I can start up Neo and start exploring the data:


$ ./neo4j-community-2.2.0/bin/neo4j start


MATCH (:Crime)-[r:CRIME_TYPE]->() 
RETURN r 
LIMIT 10

Graph 15

There’s lots more relationships and entities that we could pull out of this data set – what I’ve done is just a start. So if you’re up for some more Chicago crime exploration the code and instructions explaining how to run it are on github.

Create flexible schemas using dynamic columns for semi-structured data. Learn how.

Topics:
nosql ,spark ,neo4j ,csv file ,database

Published at DZone with permission of Michael Hunger, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

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