Machine Learning with R Cookbook - Second Edition

How to do it...

Perform the following steps to implement the word count program:

1. First, you need to configure the system environment, and then load rmr2 and rhdfs into an R session. You may need to update the use of the JAR file if you use a different version of QuickStart VM:

        > Sys.setenv(HADOOP_CMD="/usr/bin/hadoop")
        > Sys.setenv(HADOOP_STREAMING="/usr/lib/hadoop-mapreduce/hadoop        -streaming-2.5.0-cdh5.2.0.jar ")
        > library(rmr2)
        > library(rhdfs)
        > hdfs.init()

2. You can then create a directory on HDFS and put the input file into the newly created directory:

        > hdfs.mkdir("/user/cloudera/wordcount/data")
        > hdfs.put("wc_input.txt", "/user/cloudera/wordcount/data")  

3. Next, you can create a map function:

 > map = function(.,lines) { keyval( ...