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 "metadata": {
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 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "# Spark\n",
      "\n",
      "* Python Shell\n",
      "* RDDs\n",
      "* Pair RDDs"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Python Shell"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Start the pyspark shell:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "pyspark"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "View the spark context:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "sc"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## RDDs"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Create an RDD from the contents of a directory:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "my_data = sc.textFile(\"file:/path/*\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Count the number of lines in the data:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "my_data.count()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Display the data in the data:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "my_data.collect()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Return the first 10 lines in the data:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "my_data.take(10)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Create an RDD with lines matching the given filter:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "my_data.filter(lambda line: \".txt\" in line)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Chain a series of commands:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "sc.textFile(\"file:/path/file.txt\") \\\n",
      "    .filter(lambda line: \".txt\" in line) \\\n",
      "    .count()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Create a new RDD mapping each line to an array of words, taking only the first word of each array:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "first_words = my_data.map(lambda line: line.split()[0])"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Output each word in first_words:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for word in first_words.take(10):\n",
      "    print word"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Save the first words to a text file:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "first_words.saveAsTextFile(\"file:/path/file\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Pair RDDs\n",
      "\n",
      "Pair RDDs contain elements that are key-value pairs.  Keys and values can be any type."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Given a log file with the following space deilmited format: [date_time, user_id, ip_address, action], map each request to (user_id, 1):"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "DATE_TIME = 0\n",
      "USER_ID = 1\n",
      "IP_ADDRESS = 2\n",
      "ACTION = 3\n",
      "\n",
      "log_data = sc.textFile(\"file:/path/*\")\n",
      "\n",
      "user_actions = log_data \\\n",
      "    .map(lambda line: line.split()) \\\n",
      "    .map(lambda words: (words[USER_ID], 1))  \\\n",
      "    .reduceByKey(lambda count1, count2: count1 + count2)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Show the top 5 users by count, sorted in descending order:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "user_actions.map(lambda pair: (pair[0], pair[1])).sortyByKey(False).take(5)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Group IP addresses by user id:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "user_ips = log_data \\\n",
      "    .map(lambda line: line.split()) \\\n",
      "    .map(lambda words: (words[IP_ADDRESS],words[USER_ID])) \\\n",
      "    .groupByKey()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Given a user table with the following csv format: [user_id, user_info0, user_info1, ...], map each line to (user_id, [user_info...]):"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "user_data = sc.textFile(\"file:/path/*\")\n",
      "\n",
      "user_profile = user_data \\\n",
      "    .map(lambda line: line.split(',')) \\\n",
      "    .map(lambda words: (words[0], words[1:]))"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Inner join the user_actions and user_profile RDDs:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "user_actions_with_profile = user_actions.join(user_profile)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Show the joined table:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for (user_id, (user_info, count)) in user_actions_with_profiles.take(10):\n",
      "    print user_id, count, user_info"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    }
   ],
   "metadata": {}
  }
 ]
}