Hi Readers,

I am happy to post another blog post on how to use map reduce to find Max and Min temperature of a data set.

I have a dataset (say temperaturedata.txt) file. I like to analyze the above data set using map reduce.

I have a written a map reduce program to find the max and min temp of the year.

I have a data set in my linux file system and I need to move that to hadoop file system.

hdfs dfs -copyFromLocal /home/cloudera/Downloads/temperaturedata.txt /jpraveen/temperaturedata.txt

Now the file is in hdfs directory i.e (hdfs dfs -ls /jpraveen/)

Now you need to convert your map reduce program into a jar file and run the jar file using the below command.

hadoop jar MaxMinTemp.jar  /jpraveen/temperaturedata.txt  ~/output1

Note:

Below code snippet in the main method of your program

 FileInputFormat.setInputPaths(job, new Path(args[0])) represents this value /jpraveen/temperaturedata.txt.
 FileOutputFormat.setOutputPath(job, new Path(args[1])) represents this value ~/output1.

JobClient.runJob(job) this will trigger the map reduce job to start.

Moreover you can also track the job status which you will get at the time of running the map reduce.

http://quickstart.cloudera:19888/jobhistory/job/job_1479137854338_0004/

The output of the above job can seen using the below command or through file browser

hdfs dfs -cat /root/output1/part-00000 .

(or)

http://quickstart.cloudera:50070/explorer.html#/root/output5.