The brief for my final assignment is:

Your task is to write any application you like. The are no restrictions on what your application can do but it should show of the capabilities of the platform and be well written.

Marks will be awarded for interesting applications that make good use of the Android platform.

Make sure your application works on the emulator but I will also test it on a real device.

For this assignment I decided to create a Blog Reader that reads the RSS XML feeds off blogs to display them in a Android Application.
I have spent around three days coding this assignment. I will not release the code until after the assignment has been marked, however here are some screen shots of the work

My Application Sitting in the Android Application Menu on my phone

The applications home screen

Adding a new blog feed into the application

Viewing a list of blogs

Removing a blog feed

Viewing a list of blog posts

Viewing list of blog posts

Viewing single post

This one shows changes that have been made to the intersection controllers within the Traffic Simulator.

The give-way controller makes all the cars give way to all the other roads connected into the intersection with a minimum of 2.5 seconds between vehicles.

The traffic lights controller makes all the cars on the green road go at 2 second intervals and makes the others queue with a minimum wait time of 16 seconds.

The round-a-bout controller makes each car give way to the right and then go with a minimum of 3.9 seconds between each car on a road, but multiple cars from multiple roads can cross the intersection at the same time… hence the chaos on the video.

Here are hopefully some relatively clear instructions on how simple it was to do.

Setting up a MPI development system on Ubuntu Linux

1. Download Ubuntu – check out the latest version at www.ubuntu.com

2. Intall the required mpi files.

   For Ubuntu 9.04:
   In a terminal window enter:
   sudo apt-get install libopenmpi1 libopenmpi-dbg libopenmpi-dev openmpi-bin openmpi-common openmpi-dev

   For Ubuntu 10.04:
   In a terminal window enter:
   sudo apt-get install libopenmpi1.3 libopenmpi-dbg libopenmpi-dev openmpi-bin openmpi-common openmpi-dev

3. Test the mpi install by compiling and running a simple program

   1. mpicc testfile.c -o testfile

   2. mpirun -np 2 ./testfile

      1. Where np is the number of cores * number of processes on your system.

      2. e.g. on a two core laptop np should be 2.

4. If you get an error regarding ssh when you enter the mpirun command install ssh

   1. sudo apt-get install ssh

5. If you get requested for your password everytime you run mpirun set up a stored RSA key control

   1. cd $HOME

   2. ssh-keygen -t dsa

   3. cp .ssh/id_dsa.pub .ssh/authorized_keys2

Further reference:

http://www.csc.cam.ac.uk/academic/practicals.html

http://www.math.umbc.edu/~gobbert/mpi.html

For the past year and a bit I have been playing around with Virtualbox and virtualization, the major problem here however is the speed of booting, and drivers etc as it is in an emulated/simulated environment.

Enter WUBI. Wubi is an installer that allows you to install Ubuntu and Linux Mint on an NTFS partiation and use the windows boot loader so it does absolute nothing to windows at all. And to make matters better you can access your windows files straight out of the box.

I have now had a WUBI Ubunutu set up for the past week and it is brilliant.

I am now trying a new distro called Linux Mint which is aimed at end users.

If you want some help getting it installed or just want to try it out just contact me, it is brilliant just really awesome.

This morning/arvo I changed some of the code and layout of how cars were being generated. Now instead of a car know what road it is on it has been reversed, so each road has its own collection of cars to manage. With some changes to how the graphics are produced this now means that cars are now rendered at the same time as each road. A that allows perfect placement of cars onto roads rather than having to do a mathematically approximation. Clear as mud?

This is a 6,000 point balanced model, it took just under 1.5 hours to generate, compared to 4+ hours for a 5,000 point unbalanced DLA on Sunday

These strings come into the program unsorted and they must be sorted and each one must be unique. (i.e. no duplicates).

Now there are a few different ways to be able to store this data.

A SortedList, SortedDictionary, or two different forms of lists, the first where before each add you check to make sure that the data doesn’t already exist, and the second where you just add then sort then remove duplicates at a later time.

Two work out what one would be best I wrote a program to determine which form of storage operated the fastest on input. The results follow and then the code for how I did it.

As you can see the SortedDictionary worked the best, however at the early stages both the SortedList and Duplicate List gave it a run for it’s money.

Results

Sorted List Test:        00:00:00.1169883 Input:    5000    4000 List Size:    2838
Sorted Dictionary Test:  00:00:00.1339866 Input:    5000    4000 List Size:    2858
Unique List Test:        00:00:00.1119888 Input:    5000    4000 List Size:    2862
Duplicate List Test:     00:00:00.0239976 Input:    5000    4000 List Size:    2832

Sorted List Test:        00:00:01.3768623 Input:   50000   40000 List Size:   28516
Sorted Dictionary Test:  00:00:01.0678932 Input:   50000   40000 List Size:   28466
Unique List Test:        00:00:12.3097689 Input:   50000   40000 List Size:   28384
Duplicate List Test:     00:00:01.2058794 Input:   50000   40000 List Size:   28549

Sorted List Test:        00:01:36.9733017 Input:  500000  400000 List Size:  285367
Sorted Dictionary Test:  00:00:12.3307668 Input:  500000  400000 List Size:  285422
Duplicate List Test:     00:02:32.7467238 Input:  500000  400000 List Size:  285506

Sorted Dictionary Test:  00:02:37.8040000 Input: 5000000 4000000 List Size: 2854095

Code for Program.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace SortTest
{
class Program
{
public static void Main()
{
// 5,000 item list
SortedListTest.run(5000,4000);
SortedDictionaryTest.run(5000, 4000);
UniqueListTest.run(5000, 4000);
DuplicateListTest.run(5000, 4000);

// 50,000 item list
SortedListTest.run(50000, 40000);
SortedDictionaryTest.run(50000, 40000);
UniqueListTest.run(50000, 40000);
DuplicateListTest.run(50000, 40000);

// 500,000 item list
SortedListTest.run(500000, 400000);
SortedDictionaryTest.run(500000, 400000);
//UniqueListTest.run(500000, 400000);
DuplicateListTest.run(500000, 400000);

// 5,000,000 item list
//SortedListTest.run(5000000, 4000000);
SortedDictionaryTest.run(5000000, 4000000);
//UniqueListTest.run(5000000, 4000000);
//DuplicateListTest.run(5000000, 4000000);

}
}
}

Code for SortedListTest.cs
using System;
using System.Collections.Generic;
using System.Text;

namespace SortTest
{
class SortedListTest
{
private static SortedList words = null;

public static void run(int loopSize, int multiplier)
{
words = new SortedList();
DateTime startTime = DateTime.Now;
Random rand = new Random();
int i;
for (int j = 0; j != loopSize; j++)
{
i = (int)(rand.NextDouble() * multiplier);
try
{
string s = i.ToString();
words.Add(s, s[0]);
}
catch (Exception e)
{
continue;
}
}
DateTime stopTime = DateTime.Now;
TimeSpan duration = stopTime - startTime;
Console.WriteLine("Sorted List Test: " + duration.ToString() + " Input: " + loopSize + " " + multiplier + " List Size: " + words.Count);
}
}
}

Code for SortedDictionaryTest.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace SortTest
{
class SortedDictionaryTest
{
private static SortedDictionary words = null;

public static void run(int loopSize, int multiplier)
{
words = new SortedDictionary();
DateTime startTime = DateTime.Now;
Random rand = new Random();
int i;
for (int j = 0; j != loopSize; j++)
{
i = (int)(rand.NextDouble() * multiplier);
try
{
string s = i.ToString();
words.Add(s, s[0]);
}
catch (Exception e)
{
continue;
}
}
DateTime stopTime = DateTime.Now;
TimeSpan duration = stopTime - startTime;
Console.WriteLine("Sorted Dictionary Test: " + duration.ToString() + " Input: " + loopSize + " " + multiplier + " List Size: " + words.Count);
}
}
}

Code for UniqueListTest.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace SortTest
{
class UniqueListTest
{
private static List words = null;

public static void run(int loopSize, int multiplier)
{
words = new List();
DateTime startTime = DateTime.Now;
Random rand = new Random();
int i;
for (int j = 0; j != loopSize; j++)
{
i = (int)(rand.NextDouble() * multiplier);
try
{
string s = i.ToString();
bool matchfound = false;
foreach (string w in words) // ignore duplicates
{

if (w == s)
{
matchfound = true;
break;
}
}
if (!matchfound) words.Add(s);
}
catch (Exception e)
{
continue;
}
}
words.Sort();
DateTime stopTime = DateTime.Now;
TimeSpan duration = stopTime - startTime;
Console.WriteLine("Unique List Test: " + duration.ToString() + " Input: " + loopSize + " " + multiplier + " List Size: " + words.Count);
}
}
}

Code for DuplicateListTest.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace SortTest
{
class DuplicateListTest
{

private static List words = null;

public static void run(int loopSize, int multiplier)
{
words = new List();
DateTime startTime = DateTime.Now;
Random rand = new Random();
int i;
for (int j = 0; j != loopSize; j++)
{
i = (int)(rand.NextDouble() * multiplier);
try
{
string s = i.ToString();
words.Add(s);
}
catch (Exception e)
{
continue;
}
}
words.Sort();
string prev = null;
for(int counter = 0; counter < words.Count; counter++)
{

if (prev == words[counter])
{
words.RemoveAt(counter);
counter--;
}
prev = words[counter];
}
DateTime stopTime = DateTime.Now;
TimeSpan duration = stopTime - startTime;
Console.WriteLine("Duplicate List Test: " + duration.ToString() + " Input: " + loopSize + " " + multiplier + " List Size: " + words.Count);
}
}
}

This morning on my internship I was cleaning up some code I had written last friday and making sure everything worked as planned.

While checking some of the output of the program I came accross this word: Reabsorbsinged. I thought it looked a little odd and upon closer inspection of the code I found out why.

The word Reabsorbsinged is made up of one base word: absorb. From this you can combine prefix and suffix to build more words e.g. Reabsorb, Absorbs, Reabsorbs etc.

However in my blind coding last week I had failed to realise a cruicial mistake I had made when trying to take a shortcut. I had fed my input variable into a function and overwritten it at the sametime. This is a good trick if you want to minimise memory and you don’t need to worry if you input variable is overwritten.

Unfortunately I needed my input variable to stay intact to be able to generate the other words (like above). Instead I ended up with just one huge word: re+absorb+s+ing+ed So like you end up with dick of the day in some jobs I now have word of the day.

And on an entirely different note:

I am currently converting the code that generated this mistake from c++ to c#. Easy enough C# is pretty similar to java and doesn’t have pointers, yes! However as I discovered it doesn’t have a string reverse function either.

Glancing on the internet there are a few around pretty much going from extremely long and memory expensive, i.e. copying each character onto a new string at each step, or extremely quick but near impossible to read, understand or debug. So I got smart and wrote my on.

The code was a long the lines of this:


string normalString = "abcdef";
char[] tempString = normalString.toCharArray();
for(int i=0; i < tempString.length / 2; i++) {
char tempc = tempString[i];
tempString[i] = tempString[tempString.length - i -1];
tempString[tempString.length - i - 1] = tempc;
}
string reversedString = tempString.ToString();