Best way to return multiple column array

werty37

Hi

What is the best way to return <Int, Float, Float> values from a method using an array? I am trying to make a fiducial class which detects the x and y location of the fiducials identified using an ID.

I am new to processing and trying to get a hang of it. Thanks in advance.

Regards

S

KevinWorkman

Don't use an array. Create a class that contains these values and return an instance of that instead.

You could also use an array of Numbers.

GoToLoop

Java got 8 primitive types. And unfortunately, if we need to return all of those primitive types, we have to create a function for each of them: #:-S

http://docs.Oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html

void setup() {
  char[] ch = createCharArr(5);
  long[] lg = createLongArr(7);
  exit();
}

static final boolean[] createBoolArr(int len) {
  return new boolean[len];
}

static final byte[] createByteArr(int len) {
  return new byte[len];
}

static final short[] createShortArr(int len) {
  return new short[len];
}

static final char[] createCharArr(int len) {
  return new char[len];
}

static final int[] createIntArr(int len) {
  return new int[len];
}

static final long[] createLongArr(int len) {
  return new long[len];
}

static final float[] createFloatArr(int len) {
  return new float[len];
}

static final double[] createDoubleArr(int len) {
  return new double[len];
}

GoToLoop

As mentioned, create a class to encapsulate those 3 values w/ diff. datatypes: *-:)

// forum.Processing.org/two/discussion/18704/
// best-way-to-return-multiple-column-array#Item_3

// GoToLoop (2016-Oct-25)

void setup() {
  final Trio t = new Trio();
  println(t);

  t.set(MAX_INT, THIRD_PI, 1e3);
  println(t);

  t.f2 *= 1e-2;
  println(t.f2);

  t.i /= t.f1;
  println(t.i);

  println(t);
  exit();
}

static class Trio {
  int i;
  float f1, f2;

  Trio() {
  }

  Trio(int i, float f1, float f2) {
    set(i, f1, f2);
  }

  Trio set(int _i, float _f1, float _f2) {
    i  = _i;
    f1 = _f1;
    f2 = _f2;
    return this;
  }

  @ Override String toString() {
    return "[ " + i + ", " + f1 + ", " + f2 + " ]";
  }
}

Chrisir

Trio myFunction() {

}

werty37

Hi

Thanks guys. For now i am taking a simpler approach. Here is the code.

class Fiducial {

  //Change the Fiducial Marker numbers to the ones which needs to be detected. 
  //BoofCV returns false positives sometimes. 

  int[] fiducialsToDetect = {284, 643};

  Fiducial() {
  }

  float[] trackFiducialLocation(int id) {

    float[] xy = new float[2];

    List<FiducialFound> found = detector.detect(cam);

    for ( FiducialFound f : found ) {
      if (f.getId() == id) {
        xy[0] = (float) f.getImageLocation().getX();
        xy[1] = (float) f.getImageLocation().getY();
      }
      break;
    }
    return xy;
  }

  IntList detectAvailableFiducials() {

    // Detects available fiducials on the camera. 
    // Note that calling this method might return zero values because the fiducial might not be in the line of vision.
    // The return values must be checked and appended.
    // Edit int[] fiducialsToDetect variable to edit list of expected fiducial IDs.

    IntList d = new IntList();
    List<FiducialFound> found = detector.detect(cam);
    for ( FiducialFound f : found ) {
      int id = (int) f.getId();
      if (!d.hasValue(id)) {
        for (int i = 0; i<fiducialsToDetect.length; i++) {
          if (id==fiducialsToDetect[i]) {
            d.append(id);
          }
        }
      }
    }
    d.sort();
    if (debug) println(d);
    return d;
  }
}

Thanks

S

jeremydouglass

Glad you found a solution that works for you.

If you are trying to return 2 or 3 float values that relate to xyz coordinates or offsets (e.g. your float[] xy), an easy way is creating and returning a PVector object, then accessing the x y z properties. PVector is idiomatic to Processing and the class comes with a number of convenience methods.

void draw () {
  PVector fid = trackFiducialLocation();
  println(fid.x, fid.y);
}

PVector trackFiducialLocation () {
  return new PVector(10,20);
}