path: root/examples/src/main/python/sql/streaming/structured_network_wordcount.py

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"""
 Counts words in UTF8 encoded, '\n' delimited text received from the network.
 Usage: structured_network_wordcount.py <hostname> <port>
   <hostname> and <port> describe the TCP server that Structured Streaming
   would connect to receive data.

 To run this on your local machine, you need to first run a Netcat server
    `$ nc -lk 9999`
 and then run the example
    `$ bin/spark-submit examples/src/main/python/sql/streaming/structured_network_wordcount.py
    localhost 9999`
"""
from __future__ import print_function

import sys

from pyspark.sql import SparkSession
from pyspark.sql.functions import explode
from pyspark.sql.functions import split

if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Usage: structured_network_wordcount.py <hostname> <port>", file=sys.stderr)
        exit(-1)

    host = sys.argv[1]
    port = int(sys.argv[2])

    spark = SparkSession\
        .builder\
        .appName("StructuredNetworkWordCount")\
        .getOrCreate()

    # Create DataFrame representing the stream of input lines from connection to host:port
    lines = spark\
        .readStream\
        .format('socket')\
        .option('host', host)\
        .option('port', port)\
        .load()

    # Split the lines into words
    words = lines.select(
        # explode turns each item in an array into a separate row
        explode(
            split(lines.value, ' ')
        ).alias('word')
    )

    # Generate running word count
    wordCounts = words.groupBy('word').count()

    # Start running the query that prints the running counts to the console
    query = wordCounts\
        .writeStream\
        .outputMode('complete')\
        .format('console')\
        .start()

    query.awaitTermination()