Description
Problem statement:
Given a directed graph, compute the average length of the in-coming edges
for each node.
Input files:
In the input file, each line is in format of:
“EdgeId FromNodeId ToNodeId Distance”.
In the above example, the input is like:
0 0 1 10.0
1 0 2 5.0
2 1 2 2.0
3 1 3 1.0
4 2 1 3.0
5 2 3 9.0
6 2 4 2.0
7 3 4 4.0
8 4 0 7.0
9 4 3 5.0
This sample file “tiny-graph.txt” can be downloaded at:
https://webcms3.cse.unsw.edu.au/COMP9313/18s1/resources/15769
Output:
Set the number of reducers to 1. Each line in the single output file is in
format of “NodeID\tAverage length of in-coming edges”. The average
length is of double precision (using DoubleWritable). Remove the nodes
that have no in-coming edges and sort the output by NodeID in ascending
order of its numeric value. Given the example graph, the output file is like:
0\t7.0
1\t6.5
2\t3.5
3\t5.0
4\t3.0
Code format:
You are required to write TWO versions of MapReduce program to solve
this problem. The first version utilizes a combiner, and the second version
utilizes the “in-mapper combining” approach.
Write each version in a single java file (like WordCount.java used in Lab 2).
Name your first version as “EdgeAvgLen1.java”, and the second version as
“EdgeAvgLen2.java”, and put them in the package “comp9313.ass1”.
Compile:
Your java code will be compiled and packaged as a jar file, and we will use
the following commands to check the correctness of your solution:
$ $HADOOP_HOME/bin/hadoop jar YOURJAR.jar YOURCLASS input output
$ $HADOOP_HOME/bin/hdfs dfs –cat output/*
Please ensure that the code you submit can be compiled and packaged. Any
solution that has compilation errors will receive no more than 3 points for
the entire assignment.
Documentation and code readability
Your source code will be inspected and marked based on readability and
ease of understanding. The documentation (comments of the codes) in your
source code is also important. Below is an indicative marking scheme:
Result correctness: 80%
Code structure, Readability, and
Documentation: 20%
Submission:
Deadline: Sunday 1st Apr 09:59:59 PM
Log in any CSE server (e.g., williams or wagner), and use the give
command below to submit your solutions:
$ give cs9313 assignment1 EdgeAvgLen1.java EdgeAvgLen2.java
Or you can submit through:
https://cgi.cse.unsw.edu.au/~give/Student/give.php
If you submit your assignment more than once, the last submission will
replace the previous one. To prove successful submission, please take a
screenshot as assignment submission instructions show and keep it by
yourself. If you have any problems in submissions, please email to
xuefeng.chen@student.unsw.edu.au.
Late submission penalty
You will receive zero marks for this assignment.
Plagiarism:
The work you submit must be your own work. Submission of work partially
or completely derived from any other person or jointly written with any
other person is not permitted. The penalties for such an offence may include
negative marks, automatic failure of the course and possibly other academic
discipline. Assignment submissions will be examined manually.
Relevant scholarship authorities will be informed if students holding
scholarships are involved in an incident of plagiarism or other misconduct.
Do not provide or show your assignment work to any other person – apart
from the teaching staff of this subject. If you knowingly provide or show
your assignment work to another person for any reason, and work derived
from it is submitted you may be penalized, even if the work was submitted
without your knowledge or consent.
