For the past couple of days I have been doing my best to use other data that has been collected and analyzed with commercial software, like Matlab, to verify if my decision tree program is working. One common data set that is often used is something called the Fisher’s Iris Data. This data set is useful because it has been analyzed with many different algorithms and methods over the years and also because it is the example set used in the Matlab Statistics Toolbox Classification Tutorial. I will go further into how I used this data set to test my decision tree in an upcoming post. One problem with using a data set like Fisher’s Iris Data is that there are over a hundred data points for each of several factors; these take a long time to type into an array, as is required by my basic decision tree program. In Matlab a simple command like “load fisheriris” is all that is needed to load the whole data set into a collection of arrays. I wanted to find a way to do something similar with my program that would allow data to be collected and manipulated in Excel or Matlab or a simple text editor and then loaded directly into the program. There are surely multiple ways to handle this problem but I’ve got a simple solution that uses a combination of the Processing function loadString() as well as a simple method to convert arrays of Strings to arrays of Integers as described on  Manikandan’s Weblog. Enjoy the example:

// Each Processing Sketch requires a setup() and draw() function, this is the setup()
void setup()
{
  // Basic Processing setup codes
  size(640, 360);           // Create window of size 640 by 360 pixels
  background(0);            // Make window background color black
  stroke(255);              // Make stroke (line) color white
  noLoop();                 // Don't repeat (loop) the draw() fucntion

  // Load a text file with separate values (just an integer number) on each line
  // into an array of Strings, which each value in its own String
  // 100.txt contains the number 1 to 100, each on its own line
  String[] dataString = loadStrings("100.txt");
  // Print how many lines the file contained
  println("there are " + dataString.length + " lines");
  for (int i=0; i < dataString.length; i++) {
    // Print each line or number String
    println(dataString[i]);
  }
  println();             // Add a blank line to the command line ouput

  // Use custom function convertStringArraytoIntArray to convert each
  //String in an array of Strings to an integer in an array of integers
  int[] dataIntArray = convertStringArraytoIntArray(dataString);
  // Print how many numbers are in the array
  println("there are " + dataIntArray.length + " numbers in array");
  for (int i=0; i < dataIntArray.length; i++) {
    // Print each number in the array
    println(dataIntArray[i]);
  }
  println();             // Add a blank line to the comand line output
}

// Each Processing Sketch requires a setup() and draw() function
// We're not using the draw function, so we leave it blank
void draw()
{
}

// Custom Function that takes an array of Strings
// and returns an array of integers
public int[] convertStringArraytoIntArray(String[] sarray) {
  // If the array of Strings is not empty or NULL then process it
  if (sarray != null) {
    int intarray[] = new int[sarray.length];
    // Create int array with elements for each String in String array
    for (int i = 0; i < sarray.length; i++) {
      // For each String in String array, use parseInt to get integer
      intarray[i] = Integer.parseInt(sarray[i]);
    }
    return intarray;      // Return the interger array
  }
  return null;            // If the String array was null, return null
}